Filter langchain-core pydantic v1 warning on Python 3.14

langchain-core 1.2.x still touches pydantic.v1.fields in its
deprecation module, emitting a UserWarning on Python 3.14. This is
a langchain bug, not ours — filter it so pytest filterwarnings=error
doesn't fail the test suite.

Author: honnibal

pyproject.toml

@@ -22,7 +22,8 @@ filterwarnings = [
     "ignore:^.*The 'warn' method is deprecated, use 'warning' instead.*:DeprecationWarning",
     "ignore:^.*Skipping device Apple Paravirtual device that does not support Metal 2.0.*",
     "ignore:^.*was deprecated in langchain-community.*",
-    "ignore::pydantic.warnings.PydanticDeprecatedSince20"
+    "ignore::pydantic.warnings.PydanticDeprecatedSince20",
+    "ignore:Core Pydantic V1 functionality:UserWarning"
 ]
 markers = [
     "external: interacts with a (potentially cost-incurring) third-party API",