tests: Add python 3.12 support

Add it to tox.ini and pin pycodestyle to 2.10.0 until it has been
updated to fix:
hhatto/autopep8#689 and
hhatto/autopep8#696

Add python-3.12.0-rc.1 to the github workflow, and updated the Ubuntu
runner to version 22.04

.github/workflows/tests.yml

@@ -14,12 +14,12 @@ on:
 
 jobs:
   unit-tests:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       max-parallel: 5
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9, "3.10", "3.11"]
+        python-version: [3.6, 3.7, 3.8, 3.9, "3.10", "3.11", "3.12.0-rc.1"]
         include:
           - python-version: 3.6
             tox-env: py36
@@ -33,6 +33,8 @@ jobs:
             tox-env: py310
           - python-version: "3.11"
             tox-env: py311
+          - python-version: "3.12.0-rc.1"
+            tox-env: py312
     steps:
       - name: "Clone Repository"
         uses: actions/checkout@v3

tox.ini

@@ -1,5 +1,10 @@
 [tox]
-envlist = py36, py37, py38, py39, py310, py311, mypy
+envlist = py36, py37, py38, py39, py310, py311, py312, mypy
+
+[testenv:py312]
+deps =
+    -rrequirements.txt
+    pycodestyle==2.10.0
 
 [testenv]
 deps = -rrequirements.txt