fix: update actions/checkout action to v3

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v2 -> v3

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[codecov]

Codecov Report

Merging #107 (6042f0a) into master (4f3e668) will not change coverage.
The diff coverage is n/a.

❗ Current head 6042f0a differs from pull request most recent head dcf966c. Consider uploading reports for the commit dcf966c to get more accurate results

@@            Coverage Diff            @@
##            master      #107   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines           35        35           
=========================================
  Hits            35        35           

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