metrics: support strings

[paulourbano]

• ❗ I have followed the Contributing to DVC checklist.

• 📖 If this PR requires documentation updates, I have created a separate PR (or issue, at least) in dvc.org and linked it here.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01 ⚠️

Comparison is base (ac3eef4) 91.61% compared to head (55cae68) 91.60%.

❗ Current head 55cae68 differs from pull request most recent head 8f1019b. Consider uploading reports for the commit 8f1019b to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9387      +/-   ##
==========================================
- Coverage   91.61%   91.60%   -0.01%     
==========================================
  Files         487      487              
  Lines       37778    37778              
  Branches     5436     5436              
==========================================
- Hits        34610    34608       -2     
- Misses       2612     2613       +1     
- Partials      556      557       +1     

Impacted Files	Coverage Δ
dvc/utils/diff.py	82.35% <ø> (ø)
dvc/repo/metrics/show.py	96.51% <100.00%> (-2.33%)	⬇️
tests/func/metrics/test_diff.py	100.00% <100.00%> (ø)
tests/func/test_lockfile.py	100.00% <100.00%> (ø)

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[daavoo]

Thanks for the contribution @paulourbano !

Could you drop the diff change and update the tests accordingly?

[paulourbano]

Thanks for the contribution @paulourbano !

Could you drop the diff change and update the tests accordingly?

Sure, I will do the changes.
Thanks!

[paulourbano]

Test failures (tests/func/test_lockfile.py::test_cmd_changes_other_orders_are_preserved, among others) are also showing in main with latest commit 1f03c40. Root cause seems not to be related to this PR.