Upgrade test requirements.

test_requirements.txt

@@ -1,18 +1,18 @@
 appdirs==1.4.4; python_version >= '3.8'
-attrs==20.3.0; python_version >= '3.8'
-black==19.10b0; python_version >= '3.8'
-click==7.1.2; python_version >= '3.8'
-coverage==5.3
-flake8==3.8.4
-flexmock==0.10.4
-isort==5.9.1
-mccabe==0.6.1
-pluggy==0.13.1
-pathspec==0.8.1; python_version >= '3.8'
-py==1.10.0
-pycodestyle==2.6.0
-pyflakes==2.2.0
-pytest==6.2.5
-pytest-cov==2.10.1
+attrs==23.1.0; python_version >= '3.8'
+black==23.10.1; python_version >= '3.8'
+click==8.1.7; python_version >= '3.8'
+coverage==7.3.2
+flake8==6.1.0
+flexmock==0.11.3
+isort==5.12.0
+mccabe==0.7.0
+pluggy==1.3.0
+pathspec==0.11.2; python_version >= '3.8'
+py==1.11.0
+pycodestyle==2.11.1
+pyflakes==3.1.0
+pytest==7.4.2
+pytest-cov==4.1.0
 regex; python_version >= '3.8'
 typed-ast; python_version >= '3.8'

tox.ini

@@ -1,13 +1,13 @@
 [tox]
-envlist = py37,py38,py39,py310
+env_list = py37,py38,py39,py310,py311
 skip_missing_interpreters = True
-skipsdist = True
-minversion = 3.14.1
+package = editable
+minversion = 4.0
 
 [testenv]
-usedevelop = True
-deps = -rtest_requirements.txt
-passenv = COVERAGE_FILE
+deps =
+    -r test_requirements.txt
+pass_env = COVERAGE_FILE
 commands =
     pytest {posargs}
     py38,py39: black --check .
@@ -23,6 +23,7 @@ commands =
     pytest {posargs}
 
 [testenv:isort]
-deps = {[testenv]deps}
+deps =
+    {[testenv]deps}
 commands =
     isort --settings-path setup.cfg .