A11y: add alt text to EuroPython and Vercel SVGs (#775)

For #682.

Add alt text for the EuroPython logo and "Powered by Vercel" SVGs,
following
https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/SVG_In_HTML_Introduction#best_practices.

src/components/logo/logo.tsx

@@ -7,7 +7,9 @@ const LogoInverted = ({ className }: { className?: string }) => {
       fill="none"
       xmlns="http://www.w3.org/2000/svg"
       className={className}
+      aria-labelledby="svgTitle"
     >
+      <title id="svgTitle">EuroPython logo</title>
       <path
         d="M41.8318 1.58125C45.2563 1.58125 48.6232 1.85254 51.8359 2.38767C54.2701 2.79274 56.4998 3.90018 58.1163 5.50373C59.2739 6.6539 60.6545 8.60492 60.6545 11.3698V30.6774C60.6545 35.4881 56.8157 39.4013 52.0961 39.4013H31.8426C28.1097 39.4013 24.5477 40.9119 21.8125 43.6526C19.1331 46.3376 17.5965 49.9553 17.5965 53.5768V61.262H12.2042C6.36606 61.262 3.95609 56.3305 2.96385 52.1907C1.12804 44.578 1.12804 39.9364 2.96385 32.3219C3.6495 29.4604 5.08768 27.1136 7.12417 25.536C9.04917 24.044 11.4591 23.2543 14.0939 23.2543H43.5599V17.5201H23.2823V11.3716C23.2823 8.4284 23.7097 6.72822 24.7558 5.50001C25.9989 4.04325 28.3364 3.05288 32.1158 2.38582C34.9977 1.87484 38.2568 1.59798 41.5383 1.58311C41.6349 1.58311 41.7334 1.58311 41.83 1.58311M41.83 0.00371622C41.7296 0.00371622 41.6312 0.00371622 41.5308 0.00371622C38.0636 0.0204392 34.7543 0.315879 31.8408 0.830576C23.26 2.3468 21.7029 5.51859 21.7029 11.3716V19.0995H41.9805V21.6749H14.0939C8.20001 21.6749 3.04004 25.2164 1.42719 31.9558C-0.434634 39.68 -0.516391 44.4981 1.42719 52.5641C2.86909 58.5677 6.31031 62.8451 12.2042 62.8451H19.1759V53.5805C19.1759 46.8876 24.9658 40.9844 31.8426 40.9844H52.0961C57.7336 40.9844 62.2339 36.3428 62.2339 30.6812V11.3698C62.2339 5.87535 57.5979 1.74663 52.0961 0.828718C48.7124 0.26571 45.2062 0 41.8318 0L41.83 0.00371622Z"
         fill="white"
@@ -303,7 +305,9 @@ export const Logo = ({
       fill="none"
       xmlns="http://www.w3.org/2000/svg"
       className={className}
+      aria-labelledby="svgTitle"
     >
+      <title id="svgTitle">EuroPython logo</title>
       <path
         d="M148.549 5.61519C160.71 5.61519 172.666 6.57854 184.074 8.47886C192.718 9.9173 200.636 13.8499 206.377 19.5443C210.488 23.6286 215.39 30.5569 215.39 40.3752V108.939C215.39 126.022 201.758 139.918 184.998 139.918H113.076C99.8202 139.918 87.1712 145.282 77.4585 155.015C67.9437 164.549 62.4868 177.396 62.4868 190.256V217.547H43.3385C22.6065 217.547 14.0484 200.035 10.5249 185.334C4.00577 158.301 4.00577 141.818 10.5249 114.778C12.9597 104.617 18.0668 96.2829 25.2986 90.6809C32.1345 85.3825 40.6925 82.5782 50.049 82.5782H154.685V62.2157H82.6777V40.3818C82.6777 29.9301 84.1954 23.8926 87.9102 19.5311C92.3245 14.358 100.625 10.8411 114.046 8.47227C124.28 6.65772 135.854 5.67457 147.506 5.62178C147.85 5.62178 148.199 5.62178 148.542 5.62178M148.542 0.0131967C148.186 0.0131967 147.836 0.0131967 147.48 0.0131967C135.168 0.0725817 123.416 1.12172 113.07 2.94946C82.5986 8.3337 77.0692 19.5971 77.0692 40.3818V67.8243H149.077V76.9696H50.049C29.119 76.9696 10.7955 89.546 5.06811 113.478C-1.54343 140.907 -1.83375 158.017 5.06811 186.66C10.1884 207.98 22.4085 223.169 43.3385 223.169H68.0954V190.27C68.0954 166.502 88.6558 145.54 113.076 145.54H184.998C205.018 145.54 220.999 129.057 220.999 108.952V40.3752C220.999 20.8639 204.536 6.20244 184.998 2.94286C172.983 0.943562 160.532 0 148.549 0L148.542 0.0131967Z"
         fill="#0009E7"

src/components/vercel-logo.astro

@@ -4,7 +4,9 @@
   viewBox="0 0 212 44"
   fill="none"
   xmlns="http://www.w3.org/2000/svg"
+  aria-labelledby="svgTitle"
 >
+  <title id="svgTitle">Powered by Vercel</title>
   <rect width="212" height="44" rx="8" fill="black"></rect>
   <path
     d="M60.4375 15.2266V26.5H61.8438V22.4766H64.6797C66.7969 22.4766 68.3047 20.9844 68.3047 18.875C68.3047 16.7266 66.8281 15.2266 64.6953 15.2266H60.4375ZM61.8438 16.4766H64.3281C65.9609 16.4766 66.8594 17.3281 66.8594 18.875C66.8594 20.3672 65.9297 21.2266 64.3281 21.2266H61.8438V16.4766ZM73.3441 26.6484C75.7425 26.6484 77.2269 24.9922 77.2269 22.2891C77.2269 19.5781 75.7425 17.9297 73.3441 17.9297C70.9456 17.9297 69.4613 19.5781 69.4613 22.2891C69.4613 24.9922 70.9456 26.6484 73.3441 26.6484ZM73.3441 25.4375C71.7503 25.4375 70.8519 24.2812 70.8519 22.2891C70.8519 20.2891 71.7503 19.1406 73.3441 19.1406C74.9378 19.1406 75.8363 20.2891 75.8363 22.2891C75.8363 24.2812 74.9378 25.4375 73.3441 25.4375ZM89.2975 18.0781H87.9459L86.2897 24.8125H86.1647L84.2819 18.0781H82.9928L81.11 24.8125H80.985L79.3288 18.0781H77.9694L80.3288 26.5H81.6881L83.5631 19.9844H83.6881L85.5709 26.5H86.9381L89.2975 18.0781ZM93.8213 19.1172C95.1572 19.1172 96.0478 20.1016 96.0791 21.5938H91.4384C91.54 20.1016 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19.6953V17.8984C173.082 17.8438 172.738 17.8125 172.457 17.8125C171.356 17.8125 170.434 18.4375 170.199 19.2812H170.067V17.9531H168.199V26.5ZM181.7 20.8281C181.497 19.0312 180.168 17.7812 177.973 17.7812C175.403 17.7812 173.895 19.4297 173.895 22.2031C173.895 25.0156 175.411 26.6719 177.981 26.6719C180.145 26.6719 181.489 25.4688 181.7 23.6797H179.856C179.653 24.5703 178.981 25.0469 177.973 25.0469C176.653 25.0469 175.856 24 175.856 22.2031C175.856 20.4297 176.645 19.4062 177.973 19.4062C179.036 19.4062 179.676 20 179.856 20.8281H181.7ZM186.817 19.3203C187.981 19.3203 188.747 20.1328 188.786 21.3984H184.762C184.848 20.1484 185.661 19.3203 186.817 19.3203ZM188.802 24.1484C188.52 24.7812 187.856 25.1328 186.895 25.1328C185.622 25.1328 184.802 24.2422 184.755 22.8203V22.7188H190.723V22.0938C190.723 19.3984 189.262 17.7812 186.825 17.7812C184.348 17.7812 182.809 19.5078 182.809 22.2578C182.809 25.0078 184.325 26.6719 186.841 26.6719C188.856 26.6719 190.286 25.7031 190.637 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