FastAPI 0.137.0 breaks optimade server because landing.router is a plain Starlette Router

[DanielYang59]

after https://github.com/fastapi/fastapi/releases/tag/0.137.0

from optimade.server.main import main

breaks with:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
    from optimade.server.main import main as optimade
  File "/Users/yang/test-venv/.venv/lib/python3.13/site-packages/optimade/server/main.py", line 10, in <module>
    app = create_app(ServerConfig())
  File "/Users/yang/test-venv/.venv/lib/python3.13/site-packages/optimade/server/create_app.py", line 298, in create_app
    app.include_router(endpoint.router)
    ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/Users/yang/test-venv/.venv/lib/python3.13/site-packages/fastapi/applications.py", line 1553, in include_router
    self.router.include_router(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^
        router,
        ^^^^^^^
    ...<8 lines>...
        generate_unique_id_function=generate_unique_id_function,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/yang/test-venv/.venv/lib/python3.13/site-packages/fastapi/routing.py", line 2428, in include_router
    assert not router._contains_router(self), (
               ^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Router' object has no attribute '_contains_router'

likely because:

Before this, router.include_router(other_router) would take each path operation from other_router and "clone" it, or recreate it from scratch.

optimade-python-tools/optimade/server/routers/landing.py

Line 7 in d53161f

from starlette.routing import Route, Router