Drop Python 3.6 and use Python 3.10 for secondary builds

tox.ini

@@ -1,10 +1,10 @@
 [tox]
 envlist=
   linting
-  py{36,37,38,39,310}-pytestlatest
-  py38-pytestmain
-  py38-psutil
-  py38-setproctitle
+  py{37,38,39,310}-pytestlatest
+  py310-pytestmain
+  py310-psutil
+  py310-setproctitle
 isolated_build = true
 [testenv]
 extras = testing
@@ -14,14 +14,14 @@ deps =
 commands=
   pytest {posargs}
 
-[testenv:py38-psutil]
+[testenv:py310-psutil]
 extras =
   testing
   psutil
 commands =
   pytest {posargs:-k psutil}
 
-[testenv:py38-setproctitle]
+[testenv:py310-setproctitle]
 extras =
   testing
   setproctitle
@@ -40,7 +40,7 @@ commands = pre-commit run --all-files --show-diff-on-failure
 [testenv:release]
 changedir=
 description = do a release, required posarg of the version number
-basepython = python3.7
+basepython = python3.10
 skipsdist = True
 usedevelop = True
 passenv = *
@@ -50,7 +50,7 @@ commands =
   towncrier build --version {posargs} --yes
 
 [testenv:docs]
-basepython = python3
+basepython = python3.10
 usedevelop = True
 deps =
     sphinx