setup: introduce ruff

* remove unused .tx. the translation is done without transifex

* remove unused files

* remove unused checks because ruff took over

tests/test_invenio_config_tugraz.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 #
-# Copyright (C) 2020-2022 Graz University of Technology.
+# Copyright (C) 2020-2024 Graz University of Technology.
 #
 # invenio-config-tugraz is free software; you can redistribute it and/or
 # modify it under the terms of the MIT License; see LICENSE file for more
@@ -13,14 +13,14 @@ from flask import Flask
 from invenio_config_tugraz import InvenioConfigTugraz
 
 
-def test_version():
+def test_version() -> None:
     """Test version import."""
     from invenio_config_tugraz import __version__
 
     assert __version__
 
 
-def test_init():
+def test_init() -> None:
     """Test extension initialization."""
     app = Flask("testapp")
     ext = InvenioConfigTugraz(app)