fixup! FIX/ENH/CLN: simplified CheckedSession code and avoid using pydantic private API (closes #1151)

Author: gdementen

larray/core/checked.py

@@ -392,7 +392,10 @@ def _check_key_value(self, name: str,
                 # validate more than just the value type. I wonder
                 # if the type isn't available as-is somewhere in
                 # the field_info structure...
-                field_type = Annotated[field_type, *field_info.metadata]
+                # TODO: use Annotated[field_type, *field_info.metadata] when
+                #       we drop support for Python < 3.11
+                type_info = (field_type, *field_info.metadata)
+                field_type = Annotated[type_info]
 
             # see https://docs.pydantic.dev/2.12/concepts/types/#custom-types
             # for more details about TypeAdapter