Use golang 1.20 for binary test code coverage

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +10.58 :tada:

Comparison is base (586a9f1) 63.92% compared to head (6517f80) 74.50%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #44 +/- ## =========================================== + Coverage 63.92% 74.50% +10.58% =========================================== Files 3 3 Lines 255 255 =========================================== + Hits 163 190 +27 + Misses 69 51 -18 + Partials 23 14 -9 ``` [see 3 files with indirect coverage changes](https://codecov.io/gh/checkpoint-restore/checkpointctl/pull/44/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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[rst0git]

@adrianreber It might be good to add .coverage/ and checkpointctl.coverage to gitignore

[adrianreber]

@adrianreber It might be good to add .coverage/ and checkpointctl.coverage to gitignore

added