Use system FFmpeg for VP9 playback on Linux

.github/workflows/build.yml

@@ -289,9 +289,15 @@ jobs:
             clang \
             glslang-tools \
             libasound2-dev \
+            libavcodec-dev \
+            libavfilter-dev \
+            libavformat-dev \
+            libavutil-dev \
             libdbus-1-dev \
             libgl1-mesa-dev \
             libpulse-dev \
+            libswresample-dev \
+            libswscale-dev \
             libudev-dev \
             libwayland-dev \
             libx11-dev \
@@ -304,6 +310,7 @@ jobs:
             libxss-dev \
             lld \
             ninja-build \
+            pkg-config \
             wayland-protocols
 
       - name: Install Qt 6.10.3