Update README.md

[GoebelL]

Changes in this Pull Request:

• Added badge for workflow action

Mandatory checks:

• [X] latest changes were fetched from the upstream branch before creating this PR (branch is up to date)
• [X] changes were tested manually
• [ ] unit tests were properly implemented
• [ ] communication about interdependent changes has been sent to the team (if applicable)
• [ ] respective Jenkins jobs were referenced in additional context section of this PR

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This change is 

[codecov[bot]]

Codecov Report

Merging #128 (b8ddcb9) into master (0524866) will not change coverage. The diff coverage is n/a.

:exclamation: Current head b8ddcb9 differs from pull request most recent head 683eb37. Consider uploading reports for the commit 683eb37 to get more accurate results

@@           Coverage Diff           @@
##           master     #128   +/-   ##
=======================================
  Coverage   61.58%   61.58%           
=======================================
  Files         263      263           
  Lines       16840    16840           
  Branches     2199     2199           
=======================================
  Hits        10371    10371           
  Misses       5745     5745           
  Partials      724      724