tox: some cleanups & remove hardcoded python3.10

tox.ini

@@ -6,29 +6,21 @@ envlist=
   py310-psutil
   py310-setproctitle
 isolated_build = true
+
 [testenv]
-extras = testing
+extras =
+  testing
+  psutil: psutil
+  setproctitle: setproctitle
 deps =
   pytestmin: pytest==7.0.0
   pytestlatest: pytest
   pytestmain: git+https://github.com/pytest-dev/pytest.git
 commands =
-  pytest {posargs}
-
-[testenv:py310-psutil]
-extras =
-  testing
-  psutil
-commands =
-  pytest {posargs:-k psutil}
-
-[testenv:py310-setproctitle]
-extras =
-  testing
-  setproctitle
-deps = pytest
-commands =
-  pytest {posargs}
+  pytest {posargs:{env:_XDIST_TOX_DEFAULT_POSARGS:}}
+setenv =
+  _XDIST_TOX_DEFAULT_POSARGS={env:_XDIST_TOX_POSARGS_PSUTIL:}
+  psutil: _XDIST_TOX_POSARGS_PSUTIL=-k psutil
 
 [testenv:linting]
 skip_install = True
@@ -41,7 +33,6 @@ commands = pre-commit run --all-files --show-diff-on-failure
 [testenv:release]
 changedir =
 description = do a release, required posarg of the version number
-basepython = python3.10
 skipsdist = True
 usedevelop = True
 passenv = *
@@ -51,7 +42,6 @@ commands =
   towncrier build --version {posargs} --yes
 
 [testenv:docs]
-basepython = python3.10
 usedevelop = True
 deps =
     sphinx