Fix test to work with Python 3 exception names

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/tests/test_utils.py

@@ -33,14 +33,14 @@ class LoadClassTest(TestCase):
     def test_invalid_name(self):
         self.assertRaisesRegexp(
             ImproperlyConfigured,
-            'Error importing class unittest in TEST: "need more than',
+            'Error importing class unittest in TEST: .*"(not enough|need more than)',
             load_class, 'unittest', 'TEST'
         )
 
     def test_invalid_module(self):
         self.assertRaisesRegexp(
             ImproperlyConfigured,
-            'weblate.trans.tests.missing in TEST: "No module named missing"',
+            'weblate.trans.tests.missing in TEST: "No module named .*missing["\']',
             load_class, 'weblate.trans.tests.missing.Foo', 'TEST'
         )