Fix MyPy errors for _meta attribute access

Changed instance access of `self._meta.database` to class access using
`self.__class__._meta.database` to resolve MyPy type checking issues.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: abrookins

aredis_om/model/model.py

@@ -2447,7 +2447,7 @@ async def save(
                 # Connection is bound to closed event loop, refresh it and retry
                 from ..connections import get_redis_connection
 
-                self._meta.database = get_redis_connection()
+                self.__class__._meta.database = get_redis_connection()
                 db = self._get_db(pipeline)
                 await db.hset(self.key(), mapping=document)
             else:
@@ -2658,7 +2658,7 @@ async def save(
                 # Connection is bound to closed event loop, refresh it and retry
                 from ..connections import get_redis_connection
 
-                self._meta.database = get_redis_connection()
+                self.__class__._meta.database = get_redis_connection()
                 db = self._get_db(pipeline)
                 await db.json().set(self.key(), Path.root_path(), data)
             else: