fix gaw-test

[heikoklein]

Change Summary

gaw tests on PPI failed for unknown reason

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 78.36%. Comparing base (7fd10ab) to head (f920966).
Report is 3 commits behind head on main-dev.

Files with missing lines	Patch %	Lines
pyaerocom/io/gaw/reader.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           main-dev    #1415   +/-   ##
=========================================
  Coverage     78.35%   78.36%           
=========================================
  Files           137      137           
  Lines         20885    20884    -1     
=========================================
  Hits          16365    16365           
+ Misses         4520     4519    -1     

Flag	Coverage Δ
unittests	78.36% <0.00%> (+<0.01%)	⬆️

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[lewisblake]

Approved, thank you