`[testenv:]` doesn't allow lists like `[testenv:py27,py3{4,5}]`;
it only allows syntax like `[testenv:py{27,34,35}]`.
This commit changes syntax for `envlist` to make it closer to `[testenv:]`.
-envlist = py27-sqlite,py3{4,5,6,7,8,9,10,11,12,13}-sqlite,py{27,37,312}-flake8
+envlist = py{27,34,35,36,37,38,39,310,311,312,313}-sqlite,py{27,37,312}-flake8
# Base test environment settings
[testenv]
# Base test environment settings
[testenv]