packaging: add pygit2 to the py3 Windows installers This is needed to be able to use the git extension. The extension no longer complains about the library being not installed, but `hg log -r .` on a repo that works in WSL yielded a TypeError: ... File "mercurial.hg", line 188, in _peerorrepo File "mercurial.localrepo", line 3224, in instance File "mercurial.localrepo", line 623, in makelocalrepository File "hgext.git", line 117, in _makestore File "hgext.git", line 48, in __init__ TypeError: Repository unable to unpack backend. Differential Revision: https://phab.mercurial-scm.org/D9405