Add test contribution line

[UmasriMuthuvel]

This pull request adds a small test contribution line to the README file.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.05%. Comparing base (cff5d36) to head (3ffa1ef).
⚠️ Report is 57 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7213      +/-   ##
============================================
+ Coverage     78.46%   79.05%   +0.59%     
- Complexity     6730     6945     +215     
============================================
  Files           757      779      +22     
  Lines         22324    22906     +582     
  Branches       4382     4502     +120     
============================================
+ Hits          17516    18109     +593     
+ Misses         4107     4077      -30     
- Partials        701      720      +19     

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