fix: remove stack traces from non-debug output

[aduh95]

The stack traces should be irrelevant for most users of NCU, and could hide some important output.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.68%. Comparing base (9b642b0) to head (114b2a2).

Files with missing lines	Patch %	Lines
lib/verbosity.js	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #990      +/-   ##
==========================================
- Coverage   79.73%   79.68%   -0.06%     
==========================================
  Files          39       39              
  Lines        4664     4667       +3     
==========================================
  Hits         3719     3719              
- Misses        945      948       +3     

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