github: Remove ignores for failing ffmpeg tests

These no longer fail; they were fixed in ffmpeg in commit
76b33704b628248d77ed61cbef9ecd9430a4b6c5 in July 2022; we currently
test a pinned 6.0 release, where this fix is included.

.github/workflows/build.yml

@@ -489,7 +489,7 @@ jobs:
           export PATH=/llvm-mingw/bin:$PATH
           mkdir ffmpeg-build
           cd ffmpeg-build
-          ../ffmpeg/configure --samples=../fate-samples --enable-gpl --ignore-tests="vsynth1-mpeg2-422,vsynth2-mpeg2-422,vsynth3-mpeg2-422,vsynth_lena-mpeg2-422,seek-vsynth_lena-mpeg2-422"
+          ../ffmpeg/configure --samples=../fate-samples --enable-gpl
           make -j$(nproc)
           make fate-rsync
           make -j$(nproc) fate