[BUG] Swagger documents cannot be accessed directly through the browser after setting the proxy using root_path

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Issue Content

Operating System

Windows

FastAPI Version

0.109.1

Pydantic Version

2.5.3

Python Version

3.9.18

Uvicorn Version

0.27.0

from fastapi import FastAPI
import uvicorn


app = FastAPI()


@app.get('/test')
def test():
    return {'test': 'test content'}


if __name__ == '__main__':
    uvicorn.run(app='app:app', root_path='/proxy')

When I run the above code, I am unable to access the Swagger document through http://127.0.0.1:8000/docs or http://127.0.0.1:8000/proxy/docs in my browser(Not Found /proxy/openapi.json).