chore: update git2 requirement from 0.15 to 0.16

Updates the requirements on [git2](https://github.com/rust-lang/git2-rs) to permit the latest version.
- [Release notes](https://github.com/rust-lang/git2-rs/releases)
- [Commits](rust-lang/git2-rs@0.15.0...git2-curl-0.16.0)

---
updated-dependencies:
- dependency-name: git2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -23,7 +23,7 @@ paperclip-core = { path = "core", version = "0.5.2" }
 paperclip-macros = { path = "macros", version = "0.6.1", optional = true }
 
 env_logger = { version = "0.8", optional = true }
-git2 = { version = "0.15", optional = true }
+git2 = { version = "0.16", optional = true }
 heck = { version = "0.4", optional = true }
 http = { version = "0.2", optional = true }
 itertools = "0.10"