chore(api): mark PromotionMechanisms as deprecated

[hiddeco]

No description provided.

[netlify]

✅ Deploy Preview for docs-kargo-akuity-io ready!

Name	Link
🔨 Latest commit	be81f18
🔍 Latest deploy log	https://app.netlify.com/sites/docs-kargo-akuity-io/deploys/66f83c5488e73f0008b4dbeb
😎 Deploy Preview	https://deploy-preview-2594.kargo.akuity.io
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

Attention: Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.

Project coverage is 51.10%. Comparing base (c21c4cf) to head (be81f18).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/api/promote_downstream_v1alpha1.go	0.00%	0 Missing and 1 partial ⚠️
internal/controller/promotion/composite.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2594   +/-   ##
=======================================
  Coverage   51.09%   51.10%           
=======================================
  Files         282      282           
  Lines       20950    20953    +3     
=======================================
+ Hits        10705    10708    +3     
  Misses       9580     9580           
  Partials      665      665           

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

[krancour]

Thanks for the fast turnaround @hiddeco.

Small issue with linting. Naturally, we're still using deprecated things in a few places and we're getting dinged on it.

[krancour]

@hiddeco I wanted to merge this as soon as possible, so I hope you do not mind that I amended the PR with linter fixes.