Update dataclassconfig.py

Signed-off-by: Federico M. Facca <federico.facca@zaphiro.ch>

modernpython/utils/dataclassconfig.py

@@ -8,7 +8,7 @@ class DataclassConfig:  # pylint: disable=too-few-public-methods
 
     # By default, with pydantic extra arguments given to a dataclass are silently ignored.
     # This matches the default behaviour by failing noisily.
-    extra = "forbid"
+    extra = "ignore"
     populate_by_name = True
     defer_build = True
     from_attributes = True