FIX: Use correct number of default converters

unittests/test_converters.py

@@ -640,7 +640,7 @@ def test_load_converters():
     # converter classes can be loaded from their respective packages.
 
     # Please adapt, if defaults change!
-    assert len(converter_registry) == 22
+    assert len(converter_registry) == 23
 
     # All of them are contained in caoscrawler.converters
     for conv_key, conv in converter_registry.items():