chore: checkpoint before Python removal

vendor/darling/tests/compiletests.rs

@@ -0,0 +1,16 @@
+#![cfg(compiletests)]
+
+#[rustversion::stable(1.77)]
+#[test]
+fn compile_test() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/compile-fail/*.rs");
+}
+
+#[rustversion::not(stable(1.77))]
+#[test]
+fn wrong_rustc_version() {
+    panic!(
+        "This is not the expected version of rustc. Error messages vary across compiler versions so tests may produce spurious errors"
+    );
+}