ci: Upgrade pkgconf for MSVC

[amyspark]

Hi @lu-zero ,

I added a custom branch of pkgconf in https://github.com/lu-zero/cargo-c/pull/406/files#diff-bdef69ce9a0ab5d3e383332af96987a4d8561db3dbfdf9188f6eff02d87e3df2R102 . Upstream has fixed the bug, so it may be time to either set the clone back to upstream, or wait until a new release is cut.

See pkgconf/pkgconf#364