[GRASS-git] [OSGeo/grass] 505ac5: Fix Travis: ModuleNotFoundError: No module named '...

[Markus Neteler]

  Branch: refs/heads/releasebranch_8_2
  Home:   https://github.com/OSGeo/grass
  Commit: 505ac5b3c00cc8828b842ddfb35ae5eef7710930
      https://github.com/OSGeo/grass/commit/505ac5b3c00cc8828b842ddfb35ae5eef7710930
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2023-02-21 (Tue, 21 Feb 2023)

  Changed paths:
    M utils/mkhtml.py

  Log Message:
  -----------
  Fix Travis: ModuleNotFoundError: No module named 'six' (releasebranch_8_2) (#2845)

Currently Travis CI fails in `releasebranch_8_2`:

```
Traceback (most recent call last):

  File "/home/travis/build/OSGeo/grass/dist.x86_64-pc-linux-gnu/utils/mkhtml.py", line 37, in <module>
    from six.moves.urllib import request as urlrequest

ModuleNotFoundError: No module named 'six'
```

(Example for a failed Travis run: https://github.com/OSGeo/grass/pull/2843/checks?check_run_id=11475577650)

This PR addresses the removal of `six` in a simple way.

Side note: Travis does not fail in `main` due to PR #2547,
https://github.com/OSGeo/grass/commit/17fc1d8dfd5f07ac88611d22727dfd0e40cd646f#diff-3e1684c5c5d40b273b6488a9b5a5558f556d2bcf2973ba5106b6125e01aa6959