Update tests/test_router_circular_import.py

Co-authored-by: Motov Yurii <[email protected]>

tests/test_router_circular_import.py

@@ -1,11 +1,9 @@
 import pytest
-from fastapi import APIRouter, FastAPI
+from fastapi import APIRouter
 
 
 def test_router_circular_import():
-    app = FastAPI()
     router = APIRouter()
 
-    app.include_router(router)
     with pytest.raises(AssertionError, match="Cannot include router into itself"):
         router.include_router(router)