langchain-community[major]: Upgrade community to pydantic 2 (#26011)

This PR upgrades langchain-community to pydantic 2.


* Most of this PR was auto-generated using code mods with gritql
(https://github.com/eyurtsev/migrate-pydantic/tree/main)
* Subsequently, some code was fixed manually due to accommodate
differences between pydantic 1 and 2

Breaking Changes:

- Use TEXTEMBED_API_KEY and TEXTEMBEB_API_URL for env variables for text
embed integrations:
cbea780492

Other changes:

- Added pydantic_settings as a required dependency for community. This
may be removed if we have enough time to convert the dependency into an
optional one.

---------

Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/core/langchain_core/_api/deprecation.py

@@ -144,7 +144,7 @@ def deprecated(
         _package: str = package,
     ) -> T:
         """Implementation of the decorator returned by `deprecated`."""
-        from langchain_core.utils.pydantic import FieldInfoV1
+        from langchain_core.utils.pydantic import FieldInfoV1, FieldInfoV2
 
         def emit_warning() -> None:
             """Emit the warning."""
@@ -238,6 +238,25 @@ def deprecated(
                         exclude=obj.exclude,
                     ),
                 )
+        elif isinstance(obj, FieldInfoV2):
+            wrapped = None
+            if not _obj_type:
+                _obj_type = "attribute"
+            if not _name:
+                raise ValueError(f"Field {obj} must have a name to be deprecated.")
+            old_doc = obj.description
+
+            def finalize(wrapper: Callable[..., Any], new_doc: str) -> T:
+                return cast(
+                    T,
+                    FieldInfoV2(
+                        default=obj.default,
+                        default_factory=obj.default_factory,
+                        description=new_doc,
+                        alias=obj.alias,
+                        exclude=obj.exclude,
+                    ),
+                )
 
         elif isinstance(obj, property):
             if not _obj_type: