tox does not have a `skip_missing_envs` setting.

[danieljmv01]

https://github.com/twisted/towncrier/blob/27cd970aaa76167ecdc054bdb26cf6763ffa0ed8/tox.ini#L1-L4

The setting skip_missing_envs included in the [tox] section of the tox.ini is not a tox setting, at least in the most recent versions of tox. It is likely that it was confused with [skip_missing_interpreters](https://tox.wiki/en/latest/config.html#conf-skip_missing_interpreters).

[adiroiban]

Most probably.

This was introduced here https://github.com/twisted/towncrier/commit/4068ee4a7e9aaca2f2fafb44665df5e4a1ec7aab

there is also #319 which tries to prepare for tox v4.

I am not a big tox fan. I keep it's usage to the minimum.

But I am happy to review and merge any improvement on tox.