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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Release Notes

actions/checkout

v3

Compare Source

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Configuration

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[codecov]

Codecov Report

Merging #42 (4b1e657) into master (a6f9871) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #42   +/-   ##
=======================================
  Coverage   73.68%   73.68%           
=======================================
  Files           1        1           
  Lines          19       19           
  Branches        5        5           
=======================================
  Hits           14       14           
  Misses          5        5           

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