Disable parallel execution for test_gettext (#944)

Author: BCSharp

Src/IronPythonTest/Cases/CPythonCasesManifest.ini

@@ -494,6 +494,10 @@ Ignore=true
 Ignore=true
 Reason=ImportError: No module named '_testcapi'
 
+[CPython.test_gettext]
+NotParallelSafe=true
+Reason=Creates/deletes a directory with static name 'xx'
+
 [CPython.test_glob]
 Ignore=true
 Reason=Blocked by https://github.com/IronLanguages/ironpython3/issues/11