use brew to install ffmpeg

Author: ejm714

Diff for: .github/workflows/tests.yml

@@ -56,14 +56,20 @@ jobs:
 
       - uses: actions/checkout@v4
 
-      - name: Setup FFmpeg
+      - if: matrix.os == 'ubuntu-latest'
+        name: Setup FFmpeg
         uses: Iamshankhadeep/[email protected]
         with:
           # Not strictly necessary, but it may prevent rate limit
           # errors especially on GitHub-hosted macos machines.
           token: ${{ secrets.GITHUB_TOKEN }}
           version: "4.4"
 
+      - if: matrix.os == 'macos-latest'
+        name: Setup FFmpeg
+        run:
+          brew install ffmpeg@4
+
       - name: Configure Windows compilers
         uses: ilammy/msvc-dev-cmd@v1