Auto merge of #7176 - alexcrichton:update-git2, r=ehuss
Auto merge of #7176 - alexcrichton:update-git2, r=ehuss

Tighten requirements for git2 crates

Bring in a few updates, used to update libgit2 and fix a Windows issue
as well as updating the `url` dependencies.

Closes #7173

rustyhorde/cargo,vojtechkral/cargo,tsurai/cargo,tsurai/cargo,rustyhorde/cargo,rustyhorde/cargo,vojtechkral/cargo,tshepang/cargo,tshepang/cargo,rust-lang/cargo,nipunn1313/cargo,vojtechkral/cargo,eminence/cargo,tsurai/cargo,nipunn1313/cargo,vojtechkral/cargo,eminence/cargo,nipunn1313/cargo,nipunn1313/cargo,tsurai/cargo,tshepang/cargo,tshepang/cargo,rust-lang/cargo,tsurai/cargo,rust-lang/cargo,eminence/cargo,eminence/cargo,rustyhorde/cargo,rust-lang/cargo