Stop testing on Python 3.8

In production we are running on Python 3.7 and 3.9 (soon also to be
running on 3.11) so speed up tests by not running them on Python 3.8.

.github/workflows/build-and-test.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        python-version: [3.7, 3.9]
 
     steps:
       - uses: actions/checkout@v3

tox.ini

@@ -6,7 +6,7 @@
 # When changing the python or django version also change it in the tox example
 # of the documentation in hacking.rst
 [tox]
-envlist = {unit,integration,functional}-py{37,38,39}-django{32}, javascript, docs
+envlist = {unit,integration,functional}-py{37,39}-django{32}, javascript, docs
 skipsdist = True
 basepython = python3.7
 
@@ -18,7 +18,6 @@ markers =
 [gh-actions]
 python =
     3.7: py37
-    3.8: py38
     3.9: py39
 
 [testenv]