<NME> tox.ini
<BEF> [tox]
envlist =
    py{38,37,36,py3}
    style
    typing
    docs
skip_missing_interpreters = true

[testenv]
deps = -r requirements/tests.txt
commands = pytest --tb=short --basetemp={envtmpdir} {posargs}

[testenv:style]
deps = pre-commit
skip_install = true
commands = pre-commit run --all-files --show-diff-on-failure

[testenv:typing]
deps =
    -r requirements/tests.txt
    mypy
commands = mypy

[testenv:docs]
deps = -r requirements/docs.txt
commands = sphinx-build -W -b html -d {envtmpdir}/doctrees docs {envtmpdir}/html

<MSG> test python 3.9

remove style env, using pre-commit.ci
remove unused pre-commit cache step
pin mypy for tox env

<DFF> @@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{38,37,36,py3}
+    py{39,38,37,36,py3}
     style
     typing
     docs
@@ -8,7 +8,7 @@ skip_missing_interpreters = true
 
 [testenv]
 deps = -r requirements/tests.txt
-commands = pytest --tb=short --basetemp={envtmpdir} {posargs}
+commands = pytest -v --tb=short --basetemp={envtmpdir} {posargs}
 
 [testenv:style]
 deps = pre-commit
@@ -16,9 +16,7 @@ skip_install = true
 commands = pre-commit run --all-files --show-diff-on-failure
 
 [testenv:typing]
-deps =
-    -r requirements/tests.txt
-    mypy
+deps = -r requirements/typing.txt
 commands = mypy
 
 [testenv:docs]

test python 3.9