Make toml-test-harness a dev-dependency

Author: hacrvlq

integ-tests/Cargo.toml

@@ -9,9 +9,11 @@ publish = false
 codespan-reporting = "0.12"
 insta = { version = "1.34", features = ["json"] }
 pretty_assertions = "1.4"
-toml-test-harness = "0.4"
 toml-span = { workspace = true, features = ["reporting", "serde"] }
 
+[dev-dependencies]
+toml-test-harness = "0.4"
+
 [[test]]
 name = "toml_test"
 harness = false