fix: Add subversion to APT dependencies

Author: AnimMouse

.github/workflows/build-ffmpeg.yaml

@@ -79,7 +79,7 @@ jobs:
       - name: Install APT dependencies
         uses: awalsh128/cache-apt-pkgs-action@v1
         with:
-          packages: ragel cvs yasm pax nasm gperf autogen autoconf-archive
+          packages: subversion ragel cvs yasm pax nasm gperf autogen autoconf-archive
 
       - name: Install pip dependencies
         run: sudo -H pip3 -qq install meson ninja