chore: update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v5 -> v6

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Release Notes

actions/checkout (actions/checkout)

v6

Compare Source

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Configuration

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.82%. Comparing base (a4e2c1d) to head (9ed210a).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #84      +/-   ##
==========================================
+ Coverage   94.25%   94.82%   +0.56%     
==========================================
  Files          18       18              
  Lines        1689     1313     -376     
==========================================
- Hits         1592     1245     -347     
+ Misses         64       35      -29     
  Partials       33       33              

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