Added a few basic tests

tests/test_client.py

@@ -0,0 +1,8 @@
+import pytest
+
+from pyrmv import Client
+from pyrmv.classes import Stop
+
+
+def test_stop_by_name(api_client: Client):
+    assert isinstance(api_client.stop_by_name("Hauptwache", max_number=1)[0], Stop)