build(deps): update which requirement from ~3.0 to ~3.1

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)
- [Commits](harryfei/which-rs@3.0.0...3.1.0)

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

heim-process/Cargo.toml

@@ -57,7 +57,7 @@ futures-executor = "^0.3"
 version-sync = "0.8"
 pin-utils = "0.1.0-alpha.4"
 futures-timer = "0.5.0"
-which = "~3.0"
+which = "~3.1"
 
 [features]
 runtime-polyfill = ["heim-runtime/runtime-polyfill"]