Move testdummy plugin to the test directory

src/tests/testdummy/__init__.py

@@ -0,0 +1,18 @@
+from django.apps import AppConfig
+from pretix.base.plugins import PluginType
+
+
+class TestDummyApp(AppConfig):
+    name = 'tests.testdummy'
+    verbose_name = '.testdummy'
+
+    class PretixPluginMeta:
+        type = PluginType.RESTRICTION
+        name = '.testdummy'
+        version = '1.0.0'
+
+    def ready(self):
+        from tests.testdummy import signals
+
+
+default_app_config = 'tests.testdummy.TestDummyApp'