deps(renovate): update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v3 → v6

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Release Notes

actions/checkout (actions/checkout)

v6

Compare Source

v5

Compare Source

v4

Compare Source

• url-helper.ts now leverages well-known environment variables by @​jww3 in #​1941
• Expand unit test coverage for isGhes by @​jww3 in #​1946

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Configuration

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.22%. Comparing base (fce8468) to head (eb6b73e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #476      +/-   ##
==========================================
+ Coverage   96.39%   97.22%   +0.83%     
==========================================
  Files           5        5              
  Lines         361      361              
  Branches       47       48       +1     
==========================================
+ Hits          348      351       +3     
+ Misses         12       10       -2     
+ Partials        1        0       -1     

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