Added warning silencers to some noisy tests.

These warnings all emerged as the result of the introduction of the checks framework.

Thanks to Anssi Kääriäinen for the report.

tests/admin_scripts/management/commands/color_command.py

@@ -3,7 +3,7 @@ from django.core.management.base import NoArgsCommand
 
 class Command(NoArgsCommand):
     help = "Test color output"
-    requires_model_validation = False
+    requires_system_checks = False
 
     def handle_noargs(self, **options):
         return self.style.SQL_KEYWORD('BEGIN')