2d0 beta release

[matteobachetti]

• [x] Update change log
• [x] Update all the docs as relevant:
• • [x] Update notebooks
• • [x] Update pages
• [x] Check any further open issues

Already includes changes in #789

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (bfa7390) 91.46% compared to head (7cfb4cf) 78.97%.

Files	Patch %	Lines
stingray/varenergyspectrum.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #788 +/- ## =========================================== - Coverage 91.46% 78.97% -12.49% =========================================== Files 43 43 Lines 8762 8763 +1 =========================================== - Hits 8014 6921 -1093 - Misses 748 1842 +1094 ```

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[matteobachetti]

Something went wrong when rebasing. Probaby better to redo from scratch