Localization update

[nerun]

• Updated tomb.pot (recreated using generate_translatable_strings.pl);
• Updated and revised pt_BR.po translation (updated to new tomb.pot, by merging, and revised a few translations to be more accurate).
• fix issue Error in tomb.pot locale file: it's outdated #587

[Narrat]

Why change the copyright year? On one hand the script itself didn't change and therefore there is formally no need to update the claim as there is nothing new to claim. And in general only the beginning year was of importance.
In recent years there is a change on how to handle this topic in regards to the Berne convention.

The Berne Convention introduced the concept that protection exists the moment a work is "fixed", that is, written or recorded on some physical medium, and its author is automatically entitled to all copyrights in the work and to any derivative works, unless and until the author explicitly disclaims them or until the copyright expires.

Which changed recommendations and how projects adjusted:
Linux foundation on that topic
Daniel Stenberg and how he did go on with curl in that regard

Personally I would drop that specific change, but that call is up to jaromil.

And it shows that we need to change something in regards on how to handle translations and the workflow :D
Partially synced translations, weblate doing something else...

[nerun]

Reverted copyright year change.

I liked the idea of the GitHub Action in PR #557

[jaromil]

I'll let you decide when to merge this @Narrat since you are more busy on the translation front.

[nerun]

Reverted copyright year change in tomb.pot file too.

[Narrat]

Then it may be better to merge this sooner than later. Before new features or bigger changes get merged and the diff gets even bigger.
After the merge I will create a follow-up PR with the other translations and merge it directly.