fix(sanic): bind session to session class instead of to the session m…

…aker (#268)

correclty binds session into sanic extension as expected

in the original code, session maker was defined and then the dependency for
session overwrites it with a session maker as the type.  this seems
non-ideal -- you can't get the session maker and when you ask for the
session maker you get a session object

instead, this looks at the sessionmaker `class_` property for adding the sanic dependency

advanced_alchemy/extensions/sanic.py

@@ -96,6 +96,10 @@ def __init__(
             else self.sqlalchemy_config.get_engine()
         )
         self.session_maker = self.sqlalchemy_config.create_session_maker()
+
+        session_maker = cast("SessionMakerT", self.session_maker)
+        self.session_class = session_maker.class_
+
         self.app: Sanic
 
     async def _do_commit(self, session: Session | AsyncSession) -> None:
@@ -181,7 +185,7 @@ async def on_startup(_: Any) -> None:
                 self.get_sessionmaker_from_request,
             )
             bootstrap.add_dependency(
-                type(self.session_maker),
+                self.session_class,
                 self.get_session_from_request,
             )