fix: replace Type[] with type[] to match upstream imports

Upstream removed 'Type' from typing imports in favor of builtin type[].
The custom route_class/router_class parameters still used Type[], causing
NameError across all tests.

Co-authored-by: Copilot <[email protected]>

fastapi/applications.py

@@ -811,7 +811,7 @@ class FastAPI(Starlette):
             ),
         ] = True,
         route_class: Annotated[
-            Type[routing.APIRoute],
+            type[routing.APIRoute],
             Doc(
                 """
                 Custom route (*path operation*) class to be used by this router.
@@ -822,7 +822,7 @@ class FastAPI(Starlette):
             ),
         ] = routing.APIRoute,
         router_class: Annotated[
-            Type[routing.APIRouter],
+            type[routing.APIRouter],
             Doc(
                 """
                 Custom router class to be used by this application.