Update nibabel/tests/test_removalschedule.py

Co-authored-by: Chris Markiewicz <effigies@gmail.com>

Author: Remi-Gau

nibabel/tests/test_removalschedule.py

@@ -161,7 +161,7 @@ def test_attribute_removal():
 def is_gil_enabled():
     """Check if the Python GIL is enabled."""
     try:
-        sys._is_gil_enabled()
+        return sys._is_gil_enabled()
     except AttributeError:
         return True