Remove flask typing import.

Author: T4rk1n

dash/dash.py

@@ -22,7 +22,6 @@
 
 import flask
 
-from flask.typing import RouteCallable
 from importlib_metadata import version as _get_distribution_version
 
 from dash import dcc
@@ -81,6 +80,8 @@
 from ._jupyter import jupyter_dash, JupyterDisplayMode
 from .types import RendererHooks
 
+RouteCallable = Callable[..., Any]
+
 # If dash_design_kit is installed, check for version
 ddk_version = None
 if find_spec("dash_design_kit"):