Update actions/checkout action to v3

[renovate[bot]]

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`](https://togithub.com/actions/checkout/blob/HEAD/CHANGELOG.md#v310) [Compare Source](https://togithub.com/actions/checkout/compare/v2...v3) - [Use @​actions/core `saveState` and `getState`](https://togithub.com/actions/checkout/pull/939) - [Add `github-server-url` input](https://togithub.com/actions/checkout/pull/922)

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[codecov-commenter]

Codecov Report

Merging #51 (f6df352) into next (dec2830) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             next      #51   +/-   ##
=======================================
  Coverage   35.37%   35.37%           
=======================================
  Files          10       10           
  Lines         294      294           
  Branches       22       22           
=======================================
  Hits          104      104           
  Misses        190      190           

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