Try to install ffmpeg on GitHub actions using homebrew

After GitHub updated macos from version 12 to version 14, the existing action stopped working

.github/workflows/runUiTests.yml

@@ -15,11 +15,7 @@ jobs:
           distribution: zulu
           java-version: 17
       - name: Setup FFmpeg
-        uses: FedericoCarboni/setup-ffmpeg@v3
-        with:
-          # Not strictly necessary, but it may prevent rate limit
-          # errors especially on GitHub-hosted macos machines.
-          github-token: ${{ secrets.GITHUB_TOKEN }}
+        run: brew install ffmpeg
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2.4.2
       - name: Build Plugin