Update actions/checkout action to v2

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v1 -> v2

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Release Notes

actions/checkout

### [`v2`](https://togithub.com/actions/checkout/blob/master/CHANGELOG.md#v231) [Compare Source](https://togithub.com/actions/checkout/compare/v1...v2) - [Fix default branch resolution for .wiki and when using SSH](https://togithub.com/actions/checkout/pull/284)

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Configuration

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[codecov-commenter]

Codecov Report

Merging #1 (ede4ed3) into main (8c1de33) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main       #1   +/-   ##
=======================================
  Coverage   98.49%   98.49%           
=======================================
  Files           3        3           
  Lines         266      266           
=======================================
  Hits          262      262           
  Misses          4        4           

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