chore(deps): bump postcss and next

Bumps [postcss](https://github.com/postcss/postcss) to 8.4.31 and updates ancestor dependency [next](https://github.com/vercel/next.js). These dependencies need to be updated together.


Updates `postcss` from 8.4.14 to 8.4.31
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.14...8.4.31)

Updates `next` from 13.4.3 to 13.5.4
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v13.4.3...v13.5.4)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
- dependency-name: next
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

demos/base-path/package.json

@@ -14,7 +14,7 @@
     "typescript": "^4.6.3"
   },
   "dependencies": {
-    "next": "^13.4.1"
+    "next": "^13.5.4"
   },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"

demos/custom-routes/package.json

@@ -15,7 +15,7 @@
     "typescript": "^4.7.4"
   },
   "dependencies": {
-    "next": "^13.4.1"
+    "next": "^13.5.4"
   },
   "scripts": {
     "build": "next build",

demos/default/package.json

@@ -22,7 +22,7 @@
     "@reach/dialog": "^0.16.2",
     "@reach/visually-hidden": "^0.16.0",
     "@vercel/og": "^0.5.0",
-    "next": "^13.4.1",
+    "next": "^13.5.4",
     "react": "^18.2.0",
     "react-dom": "^18.2.0"
   },

demos/middleware/package.json

@@ -12,7 +12,7 @@
     "@netlify/next": "*",
     "@netlify/plugin-nextjs": "*",
     "isomorphic-unfetch": "^3.1.0",
-    "next": "^13.4.1",
+    "next": "^13.5.4",
     "react": "^18.2.0",
     "react-dom": "^18.2.0"
   },

demos/next-auth/package.json

@@ -23,7 +23,7 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "next": "^13.4.1",
+    "next": "^13.5.4",
     "next-auth": "^4.15.0",
     "nodemailer": "^6.6.3",
     "react": "^18.2.0",

demos/next-export/package.json

@@ -3,7 +3,7 @@
   "version": "1.0.0",
   "description": "",
   "dependencies": {
-    "next": "^13.4.1"
+    "next": "^13.5.4"
   },
   "devDependencies": {
     "@netlify/next": "*",

demos/next-with-edge-functions/package.json

@@ -7,7 +7,7 @@
     "start": "next start"
   },
   "dependencies": {
-    "next": "^13.4.1",
+    "next": "^13.5.4",
     "react": "^18.0.2",
     "react-dom": "^18.0.2"
   }

demos/static-root/package.json

@@ -3,7 +3,7 @@
   "version": "1.0.0",
   "description": "",
   "dependencies": {
-    "next": "^13.4.1"
+    "next": "^13.5.4"
   },
   "devDependencies": {
     "@netlify/next": "*",