Make import test run in dev mode only (#9750)

Author: bdraco

tests/test_imports.py

@@ -44,6 +44,7 @@ def test_web___all__(pytester: pytest.Pytester) -> None:
 
 
 @pytest.mark.internal
+@pytest.mark.dev_mode
 @pytest.mark.skipif(
     not sys.platform.startswith("linux") or platform.python_implementation() == "PyPy",
     reason="Timing is more reliable on Linux",