🐛 Fix `flask.escape` warning for internal tests (#9468)

* fix flask.escape warning

* 📝 Fix highlight in docs for WSGI

---------

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>

docs/en/docs/advanced/wsgi.md

@@ -12,7 +12,7 @@ Then wrap the WSGI (e.g. Flask) app with the middleware.
 
 And then mount that under a path.
 
-```Python hl_lines="2-3  22"
+```Python hl_lines="2-3  23"
 {!../../../docs_src/wsgi/tutorial001.py!}
 ```
 

docs_src/wsgi/tutorial001.py

@@ -1,6 +1,7 @@
 from fastapi import FastAPI
 from fastapi.middleware.wsgi import WSGIMiddleware
-from flask import Flask, escape, request
+from flask import Flask, request
+from markupsafe import escape
 
 flask_app = Flask(__name__)