docs: SQLAlchemyInitPlugin to SQLAlchemyPlugin fixes SerializationException for docs

docs/examples/contrib/sqlalchemy/sqlalchemy_declarative_models.py

@@ -1,3 +1,5 @@
+from __future__ import annotations # Required for forward class references, see https://peps.python.org/pep-0484/#forward-references
+
 import uuid
 from datetime import date
 from typing import TYPE_CHECKING
@@ -13,13 +15,12 @@
 if TYPE_CHECKING:
     from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession
 
-
 # the SQLAlchemy base includes a declarative model for you to use in your models.
 # The `Base` class includes a `UUID` based primary key (`id`)
 class Author(UUIDBase):
     name: Mapped[str]
     dob: Mapped[date]
-    books: Mapped[list["Book"]] = relationship(back_populates="author", lazy="selectin")
+    books: Mapped[list[Book]] = relationship(back_populates="author", lazy="selectin")
 
 
 # The `AuditBase` class includes the same UUID` based primary key (`id`) and 2
@@ -58,5 +59,6 @@ async def get_authors(db_session: "AsyncSession", db_engine: "AsyncEngine") -> l
 app = Litestar(
     route_handlers=[get_authors],
     on_startup=[on_startup],
+    debug=True,
     plugins=[SQLAlchemyPlugin(config=sqlalchemy_config)],
 )