skip xstocks tests since they are not available form the IP range of used GitHub Action runners

Author: btschwertfeger

tests/spot/test_xstocks_basic.py

@@ -17,6 +17,7 @@
 
 @pytest.mark.spot
 @pytest.mark.xstocks
+@pytest.mark.skip(reason="xStocks is only available in certain regions!")
 class TestSpotXStocks:
     """Test class for Spot xStocks client functionality."""