feat: Specify flatpak runtime (#2755)

Author: ar-lex

package.json

@@ -132,6 +132,7 @@
     "flatpak": {
       "description": "YouTube Music Desktop App bundled with custom plugins (and built-in ad blocker / downloader)",
       "category": "AudioVideo",
+      "runtimeVersion": "24.08",
       "finishArgs": [
         "--socket=wayland",
         "--socket=x11",