updated actions/checkout version

[JanStaschulat]

updated version of actions/checkout to v3

[JanStaschulat]

@mergifyio backport iron

[mergify[bot]]

backport iron

✅ Backports have been created

* [#368 updated actions/checkout version (backport #367)](https://github.com/ros2/rclc/pull/368) has been created for branch `iron`

[codecov-commenter]

Codecov Report

Merging #367 (e9bff67) into master (555192c) will decrease coverage by 0.08%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #367      +/-   ##
==========================================
- Coverage   69.63%   69.56%   -0.08%     
==========================================
  Files          16       16              
  Lines        2760     2760              
  Branches      766      766              
==========================================
- Hits         1922     1920       -2     
- Misses        452      453       +1     
- Partials      386      387       +1     

see 1 file with indirect coverage changes