CI: Add CI jobs for armv7-w64-mingw32 and aarch64-w64-mingw32
CI: Add CI jobs for armv7-w64-mingw32 and aarch64-w64-mingw32

Keep artifacts from the aarch64 build job. There's less point in
keeping artifacts from the armv7 build job, as all modern arm based
windows desktop setups are arm64 (even though they can run these armv7
binaries as well).

videolan/dav1d