chore(deps): update docker.io/library/golang docker tag to v1.21.6

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
docker.io/library/golang	stage	minor	1.20.7 -> 1.21.6

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5d39b2e) 69.45% compared to head (8dad320) 69.45%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #164 +/- ## ======================================= Coverage 69.45% 69.45% ======================================= Files 29 29 Lines 2089 2089 ======================================= Hits 1451 1451 Misses 556 556 Partials 82 82 ```

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