add dummy type fields for pkgbuild generators

This field is required in order to pass config validation in case if
section name differs from default one. Also by default keyring_generator
and mirrorlist_generator have been renamed to keyring-generator and
mirrorlist-generator respectively for consistence

tests/ahriman/application/handlers/test_handler_validate.py

@@ -64,9 +64,9 @@ def test_schema(configuration: Configuration) -> None:
     assert schema.pop("gitremote")
     assert schema.pop("html")
     assert schema.pop("keyring")
-    assert schema.pop("keyring_generator")
+    assert schema.pop("keyring-generator")
     assert schema.pop("mirrorlist")
-    assert schema.pop("mirrorlist_generator")
+    assert schema.pop("mirrorlist-generator")
     assert schema.pop("remote-pull")
     assert schema.pop("remote-push")
     assert schema.pop("report")