Badges and CI workflow updated

[konstntokas]

1. Badges for CI passing and codecov have been corrected;
2. After xcube 1.7.0 CI workflow simplified

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.93%. Comparing base (3ba749b) to head (68e1fc2).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #23   +/-   ##
=======================================
  Coverage   98.93%   98.93%           
=======================================
  Files          10       10           
  Lines         659      659           
=======================================
  Hits          652      652           
  Misses          7        7           

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