Update the Flathub badge and link

This switches the improved official badge.

As per https://fosstodon.org/@bragefuglseth/112753049810610017, this
makes Brage more peacefully at night. 🛌

README.md

@@ -37,12 +37,11 @@ The current stable version is 8 (released August 1st 2024).
 
 You can get the official Fractal Flatpak from Flathub.
 
-<a href="https://flathub.org/apps/details/org.gnome.Fractal">
+<a href="https://flathub.org/apps/org.gnome.Fractal">
 <img
-    src="https://flathub.org/assets/badges/flathub-badge-i-en.svg"
-    alt="Download Fractal on Flathub"
-    width="240px"
-    height="80px"
+    src="https://flathub.org/api/badge?svg&locale=en&light"
+    alt="Get Fractal on Flathub"
+    width="240"
 />
 </a>