redirect error messages to STDERR

[giovanni-guidini]

According to Shell Style Guide,
all error messages should go to stderr (see here)

[codecov]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (8633d98) 47.92% compared to head (8b9bf39) 47.48%.

Files	Patch %	Lines
dist/codecov_ats.sh	0.00%	7 Missing ⚠️
src/codecov_ats.sh	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #31      +/-   ##
==========================================
- Coverage   47.92%   47.48%   -0.44%     
==========================================
  Files           7        7              
  Lines         217      219       +2     
==========================================
  Hits          104      104              
- Misses        113      115       +2     

Flag	Coverage Δ
bash	37.70% <0.00%> (-0.42%)	⬇️
smart-tests	97.22% <ø> (ø)

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[thomasrockhu-codecov]

@giovanni-guidini this is fine, but can we have a run showing what it would actually look like on CI? I'm pretty sure stderr also logs on GHA, but I just want to make sure

[thomasrockhu-codecov]

Just do a run that shows that stderror actually does print out to the GHA console

[giovanni-guidini]

Just do a run that shows that stderror actually does print out to the GHA console

https://github.com/codecov/codecov-ats/actions/runs/7348125288/job/20005671013