Travis-CI: do not manually install pygit2
Travis-CI: do not manually install pygit2

Maratyszcza/NNPACK,convercraft/NNPACK,convercraft/NNPACK,Maratyszcza/NNPACK,microblink/NNPACK,microblink/NNPACK,convercraft/NNPACK,microblink/NNPACK,Maratyszcza/NNPACK,convercraft/NNPACK,Maratyszcza/NNPACK,microblink/NNPACK