userwarning repr on python3.6 adds a comma

Author: RonnyPfannschmidt

testing/test_recwarn.py

@@ -263,15 +263,15 @@ def test_as_contextmanager(self) -> None:
                 warnings.warn("user", UserWarning)
         excinfo.match(
             r"DID NOT WARN. No warnings of type \(.+RuntimeWarning.+,\) were emitted. \n"
-            r"The list of emitted warnings is: \[UserWarning\('user'\)\]."
+            r"The list of emitted warnings is: \[UserWarning\('user',?\)\]."
         )
 
         with pytest.raises(pytest.fail.Exception) as excinfo:
             with pytest.warns(UserWarning):
                 warnings.warn("runtime", RuntimeWarning)
         excinfo.match(
             r"DID NOT WARN. No warnings of type \(.+UserWarning.+,\) were emitted. \n"
-            r"The list of emitted warnings is: \[RuntimeWarning\('runtime'\)]."
+            r"The list of emitted warnings is: \[RuntimeWarning\('runtime',?\)]."
         )
 
         with pytest.raises(pytest.fail.Exception) as excinfo: