[GRASS-dev] Addons moving to Black formatting

Dear all,

Following the changes in core, we are moving grass-addons to Black formatting.

The following PR formats the grass-addons code using Black. You can see the changes by subdirectory in individual commits or just search for the file you are interested in.

https://github.com/OSGeo/grass-addons/pull/537

Open PRs will likely need to be updated before merging after #527 is merged.

Best,
Vaclav