Fix the badges in the readme (backport #234)

[mergify]

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This is an automatic backport of pull request #234 done by [Mergify](https://mergify.com).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.15%. Comparing base (3a8abba) to head (977967a).

Additional details and impacted files

@@            Coverage Diff             @@
##           humble     #236      +/-   ##
==========================================
+ Coverage   75.73%   76.15%   +0.41%     
==========================================
  Files           8        8              
  Lines         478      478              
  Branches      183      183              
==========================================
+ Hits          362      364       +2     
- Misses         71       77       +6     
+ Partials       45       37       -8     

Flag	Coverage Δ
unittests	76.15% <ø> (+0.41%)	⬆️

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see 2 files with indirect coverage changes