Fix DOI and add more badges in `README.md`

[ericpre]

Progress of the PR

• [x] Fix DOI in readme file,
• [x] add more badge in readme file,
• [n/a] docstring updated (if appropriate),
• [n/a] update user guide (if appropriate),
• [n/a] added tests,
• [x] add a changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• [x] Check formatting of the changelog entry (and eventual user guide changes) in the docs/readthedocs.org:exspy build of this PR (link in github checks)
• [x] ready for review.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.45%. Comparing base (c37013c) to head (07a4f83). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #38 +/- ## ======================================= Coverage 88.45% 88.45% ======================================= Files 67 67 Lines 7295 7295 Branches 1179 1179 ======================================= Hits 6453 6453 Misses 573 573 Partials 269 269 ```

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