fix: Callback URL file for account validation

[Darkheir]

The callback url file is the default one, url_callback and not validation_callback_url

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.78%. Comparing base (9ab4e04) to head (cccdf43).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #151      +/-   ##
==========================================
- Coverage   90.78%   90.78%   -0.01%     
==========================================
  Files          35       35              
  Lines        2485     2484       -1     
==========================================
- Hits         2256     2255       -1     
  Misses        229      229              

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[github-actions]

Test Results

221 tests  ±0   220 ✅ ±0   1m 46s ⏱️ +3s
  1 suites ±0     1 💤 ±0 
  1 files   ±0     0 ❌ ±0 

Results for commit cccdf43. ± Comparison against base commit 9ab4e04.