feat: Add Python 3.8 test.

Author: mike-oakley

tox.ini

@@ -1,9 +1,10 @@
 [tox]
 min_version = 4.0
-env_list = format, lint, py{39,310,311}-pydantic{1,2}-{test,type}
+env_list = format, lint, py{38,39,310,311}-pydantic{1,2}-{test,type}
 
 [gh-actions]
 python =
+    3.8: py38
     3.9: py39
     3.10: py310
     3.11: format, lint, py311