Bump which from 4.1.0 to 4.2.1 (use-ink#315)

Bumps [which](https://github.com/harryfei/which-rs) from 4.1.0 to 4.2.1.
- [Release notes](https://github.com/harryfei/which-rs/releases)
- [Commits](harryfei/which-rs@4.1.0...4.2.1)

---
updated-dependencies:
- dependency-name: which
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.toml

@@ -28,7 +28,7 @@ zip = { version = "0.5.13", default-features = false }
 parity-wasm = "0.42.2"
 cargo_metadata = "0.14.0"
 codec = { package = "parity-scale-codec", version = "2.1", features = ["derive"] }
-which = "4.1.0"
+which = "4.2.1"
 colored = "2.0.0"
 toml = "0.5.8"
 rustc_version = "0.4.0"