Fixed integration icon background for Night shift

refs. TryGhost@ee4edce

The blending mode used on light theme didn't work for Night shift (made all the icons blend into the dark background).

app/styles/app-dark.css

@@ -370,4 +370,8 @@ input:focus,
 
 .gh-nav-list .gh-nav-nightshift span svg path {
     fill: color-mod(var(--midgrey) l(-5%));
+}
+
+.apps-card-app-icon {
+    mix-blend-mode: normal;
 }