Bump to ffmpeg 7.1.2

vcpkg bump to ffmpeg 7.1.2 was done in
microsoft/vcpkg#47384.

Closes Vita3K#21.

Author: xerpi

.github/workflows/build.yml

@@ -91,7 +91,7 @@ jobs:
         run: |
           (cd ${{ matrix.vcpkg-root }} && git fetch origin)
           (cd ${{ matrix.vcpkg-root }} && git reset --hard)
-          (cd ${{ matrix.vcpkg-root }} && git checkout 41f90cc7b84116517b01f729af17fc735e9cd821)
+          (cd ${{ matrix.vcpkg-root }} && git checkout 34823ada10080ddca99b60e85f80f55e18a44eea)
           (cd ${{ matrix.vcpkg-root }} && git apply --ignore-space-change --ignore-whitespace --3way ${{ github.workspace }}/ffmpeg.patch)
 
       - name: Build ffmpeg