test_import skip test_unencodable_filename until posix NFI based support is in

Author: cosminbasca

graalpython/lib-python/3/test/test_import/__init__.py

@@ -1267,6 +1267,7 @@ def exec_module(*args):
             else:
                 importlib.SourceLoader.exec_module = old_exec_module
 
+    @impl_detail("[GR-27024] [GR-23324] posix NFI support", graalvm=False)
     @unittest.skipUnless(TESTFN_UNENCODABLE, 'need TESTFN_UNENCODABLE')
     def test_unencodable_filename(self):
         # Issue #11619: The Python parser and the import machinery must not