Move `rusty-fork` to dev-dependencies

Cargo.toml

@@ -67,7 +67,6 @@ bytesize = { version = "1.3.0" }
 encoding_rs = "0.8.33"
 os_str_bytes = { version = "~6.6", optional = true }
 run_script = { version = "^0.10.1", optional = true}
-rusty-fork = "0.3.0"
 
 [dependencies.git2]
 version = "0.18"
@@ -94,6 +93,7 @@ expect-test = "1.4.1"
 serial_test = { version = "2.0.0", default-features = false }
 predicates = "3.0.4"
 wait-timeout = "0.2.0"
+rusty-fork = "0.3.0"
 tempfile = "3.8.1"
 
 [target.'cfg(unix)'.dev-dependencies]