core[patch]: fix beta, deprecated typing (#18877)

**Description:** 

While not technically incorrect, the TypeVar used for the `@beta`
decorator prevented pyright (and thus most vscode users) from correctly
seeing the types of functions/classes decorated with `@beta`.

This is in part due to a small bug in pyright
(https://github.com/microsoft/pyright/issues/7448 ) - however, the
`Type` bound in the typevar `C = TypeVar("C", Type, Callable)` is not
doing anything - classes are `Callables` by default, so by my
understanding binding to `Type` does not actually provide any more
safety - the modified annotation still works correctly for both
functions, properties, and classes.

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/cache.py

@@ -403,7 +403,7 @@ class _RedisCacheBase(BaseCache, ABC):
         if results:
             for _, text in results.items():
                 try:
-                    generations.append(loads(text))
+                    generations.append(loads(cast(str, text)))
                 except Exception:
                     logger.warning(
                         "Retrieving a cache value that could not be deserialized "