fix: only PUT a ruleset when an ID already exists

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes 🐛 Bug: Occasional error in transition mode: The branch-ruleset-update request failed #1967
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

If options.rulesetId doesn't exist, then transition mode should still POST a new ruleset, not PUT to update an existing one.

🎁

[codecov]

Codecov Report

Attention: Patch coverage is 20.51282% with 62 lines in your changes missing coverage. Please review.

Project coverage is 94.85%. Comparing base (5dd93c0) to head (29a7c28).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/blocks/blockRepositoryBranchRuleset.ts	20.51%	62 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1968      +/-   ##
==========================================
- Coverage   95.55%   94.85%   -0.70%     
==========================================
  Files          91       91              
  Lines        3643     3655      +12     
  Branches      214      214              
==========================================
- Hits         3481     3467      -14     
- Misses        162      188      +26     

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[github-actions]

🎉 This is included in version v2.4.1 🎉

The release is available on:

• GitHub releases
• npm package (@latest dist-tag)

Cheers! 📦🚀