Revert "chore: disable warnings in old CI (#4691)"

This reverts commit b24df49a9d so we can
merge the CHANGELOG changes in #4691 into master.

tests-build/tests/pass/forward_args_and_output.rs

@@ -0,0 +1,13 @@
+use tests_build::tokio;
+
+fn main() {}
+
+// arguments and output type is forwarded so other macros can access them
+
+#[tokio::test]
+async fn test_fn_has_args(_x: u8) {}
+
+#[tokio::test]
+async fn test_has_output() -> Result<(), Box<dyn std::error::Error>> {
+    Ok(())
+}