Update actions/checkout action to v4

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v3 -> v4

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Release Notes

actions/checkout (actions/checkout)

v4

Compare Source

• Support fetching without the --progress option
• Update to node20

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Configuration

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[codecov]

Codecov Report

Merging #145 (ee245ef) into main (5273d71) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #145   +/-   ##
=======================================
  Coverage   85.62%   85.62%           
=======================================
  Files          19       19           
  Lines        1120     1120           
=======================================
  Hits          959      959           
  Misses        124      124           
  Partials       37       37           

Flag	Coverage Δ
unittests	85.62% <ø> (ø)

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