fix: restore missing section in unstable release notes

[dlachaume]

Content

This PR includes a fix that restores a section missing from the unstable release notes (Fetch the latest version of the unstable tag) due to an incorrect input reference. The version-name input was removed in favor of tag.
This regression was introduced after the merge of #2646.

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • CHANGELOG file is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested
• Documentation
  • Update README file (if relevant)
  • Update documentation website (if relevant)
  • Add dev blog post (if relevant)
  • Add ADR blog post or Dev ADR entry (if relevant)
  • No new TODOs introduced

Relates to #2638

[github-actions]

Test Results

    4 files  ±0    154 suites  ±0   22m 32s ⏱️ -56s
2 118 tests ±0  2 118 ✅ ±0  0 💤 ±0  0 ❌ ±0 
6 466 runs  ±0  6 466 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 4bb1b2d. ± Comparison against base commit 78f6fcd.

[turmelclem]

LGTM 🦒