Add checkpointctl version

[rst0git]

This pull request adds --version option for the checkpointctl tool.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.14 :tada:

Comparison is base (0560541) 63.77% compared to head (feac42f) 63.92%.

:exclamation: Current head feac42f differs from pull request most recent head 3e0ecd3. Consider uploading reports for the commit 3e0ecd3 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #42 +/- ## ========================================== + Coverage 63.77% 63.92% +0.14% ========================================== Files 3 3 Lines 254 255 +1 ========================================== + Hits 162 163 +1 Misses 69 69 Partials 23 23 ``` | [Impacted Files](https://codecov.io/gh/checkpoint-restore/checkpointctl/pull/42?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [checkpointctl.go](https://codecov.io/gh/checkpoint-restore/checkpointctl/pull/42?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Y2hlY2twb2ludGN0bC5nbw==) | `66.03% <100.00%> (+0.65%)` | :arrow_up: | 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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[adrianreber]

What about passing the version from the Makefile. Search for main.name for an example.

[rst0git]

Thanks @adrianreber! I've updated the pull request to pass the version from the Makefile using main.version.