Add misc script to find missing towncrier news files

[sklam]

The script finds missing towncrier files by scanning for merge commits that are not already in the CHANGE_LOG or not have the skip_release_notes label on github for the PR.

[guilhermeleobas]

@sklam, could you list in the script the set of libraries it depends?

• github.py
• gitpython
• docopt

Am I missing any other lib?

[sklam]

RE: #9101 (comment)

I have added the list to the script.

[guilhermeleobas]

LGTM. Can confirm it works.

Could you include as well an example of how to use it?

[sklam]

If you run the script on this branch, you will see:

> python maint/towncrier_checker.py  --token=insert_gh_token --beginning=0.58.0dev0 --repo=numba/numba
Removing 8982 as already in CHANGELOG
Removing 8932 as already in CHANGELOG
Removing 9004 as already in CHANGELOG
Removing 8929 as already in CHANGELOG
Removing 8964 as already in CHANGELOG
Removing 8958 as already in CHANGELOG
Removing 8895 as already in CHANGELOG
Removing 8976 as already in CHANGELOG
Removing 8896 as already in CHANGELOG
Removing 8998 as already in CHANGELOG
Removing 9005 as already in CHANGELOG
Removing 8978 as already in CHANGELOG
Removing 9006 as already in CHANGELOG
Removing 8996 as already in CHANGELOG
Removing 8902 as already in CHANGELOG
Removing 8909 as already in CHANGELOG
Removing 8947 as already in CHANGELOG
Removing 8965 as already in CHANGELOG
Removing 8907 as already in CHANGELOG
PRs that are missing towncrier notes and not skipped
7262 https://github.com/numba/numba/pull/7262
7543 https://github.com/numba/numba/pull/7543
8462 https://github.com/numba/numba/pull/8462
8885 https://github.com/numba/numba/pull/8885
8892 https://github.com/numba/numba/pull/8892
8906 https://github.com/numba/numba/pull/8906
8911 https://github.com/numba/numba/pull/8911
8916 https://github.com/numba/numba/pull/8916
8944 https://github.com/numba/numba/pull/8944
8974 https://github.com/numba/numba/pull/8974
8988 https://github.com/numba/numba/pull/8988
8995 https://github.com/numba/numba/pull/8995
9035 https://github.com/numba/numba/pull/9035

The Removing XXXX as already in CHANGELOG are showing PR merged that are already mentioned in the CHANGE_LOG, which indicates they are included in a previous release. No action needed for these.

Everything else under PRs that are missing towncrier notes and not skipped are the PRs that are missing towncrier news fragment and they don't have the skip_release_notes label on GH.

[guilhermeleobas]

Thanks, Siu! Already approved the PR.