Try building fewer things from source.

.github/workflows/main.yml

@@ -28,9 +28,8 @@ jobs:
         brew install cairo --build-from-source
         brew install harfbuzz --build-from-source
         brew install libass --build-from-source
-        brew install ffmpeg --build-from-source
         brew install ninja
-        brew install mpv --build-from-source
+        brew install mpv
     - name: Debug build and test
       run: |
         ./download_webclient.sh