Update get_return_annotation test

Author: kianelbo

testing/python/fixtures.py

@@ -5097,7 +5097,7 @@ def six() -> int:
     def two_sixes() -> tuple[int, str]:
         return (6, "six")
 
-    assert get_return_annotation(two_sixes) == "Tuple[int, str]"
+    assert get_return_annotation(two_sixes) == "tuple[int, str]"
 
     def no_annot():
         return 6