Widen the response typing

Whilst not strictly true for Flask, it is true for Flask and Quart and
hence makes it much easier for Quart to extend Flask classes. The
alternatives are generic usage in the sansio codebase or mixed usage
within Flask. I think this is a good compromise.

src/flask/typing.py

@@ -5,7 +5,7 @@
 if t.TYPE_CHECKING:  # pragma: no cover
     from _typeshed.wsgi import WSGIApplication  # noqa: F401
     from werkzeug.datastructures import Headers  # noqa: F401
-    from werkzeug.wrappers import Response  # noqa: F401
+    from werkzeug.sansio.response import Response  # noqa: F401
 
 # The possible types that are directly convertible or are a Response object.
 ResponseValue = t.Union[