refactor: order by key when printing labels

[phm07]

This PR adds sorting of labels by their keys, which is useful for testing, since iteration order over maps in Go is undefined by default.
It uses the Go 1.23 iteration feature. If we want to use this, we should probably bump the Go version in a separate PR.

[codecov]

Codecov Report

Attention: Patch coverage is 63.15789% with 7 lines in your changes missing coverage. Please review.

Project coverage is 70.17%. Comparing base (138a10a) to head (3514764).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/cmd/util/util.go	62.50%	2 Missing and 1 partial ⚠️
internal/cmd/loadbalancer/describe.go	0.00%	1 Missing ⚠️
internal/cmd/primaryip/describe.go	0.00%	1 Missing ⚠️
internal/cmd/server/describe.go	0.00%	1 Missing ⚠️
internal/cmd/volume/describe.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #960      +/-   ##
==========================================
+ Coverage   63.66%   70.17%   +6.50%     
==========================================
  Files         243      245       +2     
  Lines       10719    10782      +63     
==========================================
+ Hits         6824     7566     +742     
+ Misses       3180     2539     -641     
+ Partials      715      677      -38     

Flag	Coverage Δ
e2e	46.94% <57.89%> (?)
unit	63.63% <57.89%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[apricote]

Personally I do not think this is worth bumping the Go dependency before 1.24 is released and 1.22 becomes EOL anyway.

[phm07]

Personally I do not think this is worth bumping the Go dependency before 1.24 is released and 1.22 becomes EOL anyway.

I initially created this PR because the undeterministic behavior of label output made it difficult to test output in the e2e tests. Since the CLI is not a library I don't see any drawbacks from upgrading to a newer Go version.

On that note, we could also test the new tool directive here once Go 1.24 releases.

[phm07]

This already causes the CI to fail randomly: https://github.com/hetznercloud/cli/actions/runs/12893320728/job/35949486386#step:5:527

[phm07]

Since #991 was merged, we now require Go 1.23, so this PR doesn't bump the Go version anymore.

[apricote]

I do not think this is worthy of being added to the Changelog, does not really matter for customers and is more about test behaviour. I updated the title for this.