Remove redundant import

Author: markshannon

Lib/test/test_gc.py

@@ -6,7 +6,6 @@
 from test.support.os_helper import temp_dir, TESTFN, unlink
 from test.support.script_helper import assert_python_ok, make_script
 from test.support import threading_helper, gc_threshold
-from test.support import Py_GIL_DISABLED
 
 import gc
 import sys