[cleanup] Remove Python 3.8 env from tox

Author: ulgens

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{38,39,310}-django{42,50}-djangorestframework{314}{,-pytest}
+    py{39,310}-django{42,50}-djangorestframework{314}{,-pytest}
     py{311}-django{42}-djangorestframework{314}{,-pytest}
     py{311,312}-django{50}-djangorestframework{315}{,-pytest}
     py{311,312}-django{51}-djangorestframework{315}{,-pytest}