Add latest flask 2.x release to CI runs

Author: vimalloc

tox.ini

@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py37,py38,py39,py310,py311,py312,pypy3.9,flask21,mypy,coverage,style,docs
+envlist = py37,py38,py39,py310,py311,py312,pypy3.9,flask21,flask2x,mypy,coverage,style,docs
 
 [testenv]
 commands =
@@ -15,6 +15,8 @@ deps =
   python-dateutil
   flask21: Flask>=2.1,<2.2
   flask21: Werkzeug>=2,<3
+  flask2x: Flask<3.0
+  flask2x: Werkzeug>=2,<3
 
 [testenv:mypy]
 commands =