Update workflow.yml

Trying to fix Ffmpeg build

.github/workflows/workflow.yml

@@ -29,7 +29,13 @@ jobs:
       - name: Install ffmpeg with development headers
         run: |
           sudo apt update
-          sudo apt install -y ffmpeg libavcodec-dev libavformat-dev libavfilter-dev libavdevice-dev libswscale-dev libavutil-dev libswresample-dev
+          sudo apt install -y software-properties-common
+          sudo add-apt-repository -y ppa:jonathonf/ffmpeg-4
+          sudo apt update
+          sudo apt install -y ffmpeg=6.* libavcodec-dev=6.* libavformat-dev=6.* libavfilter-dev=6.* libavdevice-dev=6.* libswscale-dev=6.* libavutil-dev=6.* libswresample-dev=6.*
+          
+      - name: Ffmpeg version check (just to be sure it's version 6 until the bindings are fixed for version 7)
+        run: ffmpeg -version
 
       - name: Install dependencies
         run: opam install . --deps-only --with-test