[frontend] Fix url for exercise

[Dimfacion]

Proposed changes

• Fix on the url

Related issues

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.62%. Comparing base (f902de8) to head (b7b6ab8).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1374   +/-   ##
=========================================
  Coverage     28.62%   28.62%           
  Complexity     1319     1319           
=========================================
  Files           526      526           
  Lines         13731    13731           
  Branches        814      814           
=========================================
  Hits           3930     3930           
  Misses         9616     9616           
  Partials        185      185           

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