build: bump FFmpeg from "gpl 6.0" to "gpl 6.1"

Author: bastimeyer

.github/workflows/build.yml

@@ -129,7 +129,7 @@ jobs:
           - win32
           - win64
         variant:
-          - gpl 6.0
+          - gpl 6.1
     steps:
       - name: Free Disk-Space
         run: df -h && sudo apt-get clean && docker system prune -a -f && sudo rm -rf /usr/local/lib/android /usr/share/dotnet /opt/ghc && df -h
@@ -178,7 +178,7 @@ jobs:
           - win32
           - win64
         variant:
-          - gpl 6.0
+          - gpl 6.1
     steps:
       - name: Free Disk-Space
         run: df -h && sudo apt-get clean && docker system prune -a -f && sudo rm -rf /usr/local/lib/android /usr/share/dotnet /opt/ghc && df -h