sqlalchemy MovedIn20Warning declarative_base DEPRICATION fix (#5676)

fix for the sqlalchemy deprecated declarative_base import :

```
MovedIn20Warning: The ``declarative_base()`` function is now available as sqlalchemy.orm.declarative_base(). (deprecated since: 2.0) (Background on SQLAlchemy 2.0 at: https://sqlalche.me/e/b8d9)
  Base = declarative_base()  # type: Any
```

Import is wrapped in an try catch Block to fallback to the old import if
needed.

---------

Co-authored-by: Dev 2049 <dev.dev2049@gmail.com>

langchain/memory/chat_message_histories/sql.py

@@ -3,7 +3,11 @@ import logging
 from typing import List
 
 from sqlalchemy import Column, Integer, Text, create_engine
-from sqlalchemy.ext.declarative import declarative_base
+
+try:
+    from sqlalchemy.orm import declarative_base
+except ImportError:
+    from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
 from langchain.schema import (

langchain/vectorstores/analyticdb.py

@@ -8,7 +8,11 @@ from typing import Any, Dict, Iterable, List, Optional, Tuple
 import sqlalchemy
 from sqlalchemy import REAL, Index
 from sqlalchemy.dialects.postgresql import ARRAY, JSON, UUID
-from sqlalchemy.ext.declarative import declarative_base
+
+try:
+    from sqlalchemy.orm import declarative_base
+except ImportError:
+    from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import Session, relationship
 from sqlalchemy.sql.expression import func