fix: move supertest to dev dependencies

[andypols]

Summary

The testing library supertest was accidentally install as a main dependency. This PR moves it to a dev dependency.

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	93f9608
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/69406b9b3eecad00082bbaae

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.65%. Comparing base (6e7fea1) to head (93f9608).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1328   +/-   ##
=======================================
  Coverage   80.65%   80.65%           
=======================================
  Files          65       65           
  Lines        4575     4575           
  Branches      774      774           
=======================================
  Hits         3690     3690           
  Misses        870      870           
  Partials       15       15           

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