Import NoReturn from typing module

This no longer needs the mypy-extensions library, so it can be
eliminated now.

tildes/requirements-dev.in

@@ -3,7 +3,6 @@ black
 freezegun
 ipython
 mypy
-mypy-extensions
 prospector
 pyramid-debugtoolbar
 pyramid-ipython

tildes/tildes/models/user/user.py

@@ -4,9 +4,8 @@
 """Contains the User class."""
 
 from datetime import datetime, timedelta
-from typing import Any, List, Optional, Sequence, Tuple
+from typing import Any, List, NoReturn, Optional, Sequence, Tuple
 
-from mypy_extensions import NoReturn
 from pyotp import TOTP
 from pyramid.security import (
     ALL_PERMISSIONS,

tildes/tildes/views/login.py

@@ -3,10 +3,10 @@
 
 """Views related to logging in/out."""
 
+from typing import NoReturn
 from urllib.parse import unquote_plus
 
 from marshmallow.fields import String
-from mypy_extensions import NoReturn
 from pyramid.httpexceptions import HTTPFound, HTTPUnauthorized, HTTPUnprocessableEntity
 from pyramid.renderers import render_to_response
 from pyramid.request import Request

tildes/tildes/views/shortener.py

@@ -3,7 +3,8 @@
 
 """Views related to the link shortener."""
 
-from mypy_extensions import NoReturn
+from typing import NoReturn
+
 from pyramid.httpexceptions import HTTPMovedPermanently
 from pyramid.request import Request
 from pyramid.security import NO_PERMISSION_REQUIRED