Improvement: Update release strategy

[Davknapp]

Closes #2095
Closes #2053
Make a proper tagged release and add a tarball of that version as an asset to the release.
An example can be found here: https://github.com/DLR-AMR/t8code/releases/tag/v4.0.0-26.01

All these boxes must be checked by the AUTHOR before requesting review:

• The PR is small enough to be reviewed easily. If not, consider splitting up the changes in multiple PRs.
• The title starts with one of the following prefixes: Documentation:, Bugfix:, Feature:, Improvement: or Other:.
• If the PR is related to an issue, make sure to link it.
• The author made sure that, as a reviewer, he/she would check all boxes below.

All these boxes must be checked by the REVIEWERS before merging the pull request:

As a reviewer please read through all the code lines and make sure that the code is fully understood, bug free, well-documented and well-structured.

General

• The reviewer executed the new code features at least once and checked the results manually.
• The code follows the t8code coding guidelines.
• New source/header files are properly added to the CMake files.
• The code is well documented. In particular, all function declarations, structs/classes and their members have a proper doxygen documentation. Make sure to add a file documentation for each file!
• All new algorithms and data structures are sufficiently optimal in terms of memory and runtime (If this should be merged, but there is still potential for optimization, create a new issue).

Tests

• The code is covered in an existing or new test case using Google Test.
• The code coverage of the project (reported in the CI) should not decrease. If coverage is decreased, make sure that this is reasonable and acceptable.
• Valgrind doesn't find any bugs in the new code. This script can be used to check for errors; see also this wiki article.

If the Pull request introduces code that is not covered by the github action (for example coupling with a new library):

• Should this use case be added to the github action?
• If not, does the specific use case compile and all tests pass (check manually).

Scripts and Wiki

• If a new directory with source files is added, it must be covered by the script/find_all_source_files.scp to check the indentation of these files.
• If this PR introduces a new feature, it must be covered in an example or tutorial and a Wiki article.

License

• The author added a BSD statement to doc/ (or already has one).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.35%. Comparing base (2625544) to head (e5c2025).
⚠️ Report is 188 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2094      +/-   ##
==========================================
+ Coverage   77.05%   77.35%   +0.30%     
==========================================
  Files         112      113       +1     
  Lines       18959    19124     +165     
==========================================
+ Hits        14608    14793     +185     
+ Misses       4351     4331      -20     

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[sandro-elsweijer]

This it again this type of review where we cannot really check if it works until it is merged and runs, right?

[sandro-elsweijer]

I like that you re-used the tarball job :)

[Davknapp]

I like that you re-used the tarball job :)

Thanks! It made things so much easier!

[Davknapp]

This it again this type of review where we cannot really check if it works until it is merged and runs, right?

Actually, no! I have made it callable via a workflow dispatch. If you delete the the current monthly release, you trigger the workflow manually (if you use this branch) and check if it works.