Update which requirement from 5.0 to 6.0

Updates the requirements on [which](https://github.com/harryfei/which-rs) to permit the latest version.
- [Release notes](https://github.com/harryfei/which-rs/releases)
- [Changelog](https://github.com/harryfei/which-rs/blob/master/CHANGELOG.md)
- [Commits](harryfei/which-rs@5.0.0...6.0.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -19,7 +19,7 @@ regex = "1"
 tempfile = "3"
 thiserror = "1.0.34"
 
-which = { version = "5.0", optional = true }
+which = { version = "6.0", optional = true }
 
 [badges]
 maintenance = { status = "passively-maintained" }