ci: mark the app as a game so macOS Game Mode can activate

macOS Game Mode (Sonoma+) activates automatically when an app whose
LSApplicationCategoryType is public.app-category.games runs frontmost in
full screen. Set the category in the bundle Info.plist so picking the
Fullscreen display mode triggers Game Mode (CPU/GPU prioritisation,
lower input/audio latency).

Author: Mearman

.github/workflows/macos-build.yml

@@ -555,6 +555,8 @@ jobs:
               <string>6.0</string>
               <key>CFBundlePackageType</key>
               <string>APPL</string>
+              <key>LSApplicationCategoryType</key>
+              <string>public.app-category.games</string>
               <key>LSMinimumSystemVersion</key>
               <string>13.0</string>
               <key>NSHighResolutionCapable</key>