chore: bump Mattraks/delete-workflow-runs from v2.0.6 to v2.1 (Node.js 20 deprecation)

[gandalf-at-lerian]

Problem

The composite action src/config/workflow-runs-cleanup/action.yml pins Mattraks/delete-workflow-runs to v2.0.6 (SHA 39f0bbed25d76b34de5594dceab824811479e5de), which targets Node.js 20.

GitHub deprecated Node.js 20 on Actions runners (see changelog) and is currently forcing affected actions to run on Node.js 24. This generates a warning on every Delete old workflow runs job run:

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24:
Mattraks/delete-workflow-runs@39f0bbed25d76b34de5594dceab824811479e5de

Example run: https://github.com/LerianStudio/github-actions-shared-workflows/actions/runs/27929980275

Fix

Update the pin in src/config/workflow-runs-cleanup/action.yml to Mattraks/delete-workflow-runs@v2.1 (released Nov 2025), which should use Node.js 22+.

-      uses: Mattraks/delete-workflow-runs@39f0bbed25d76b34de5594dceab824811479e5de # v2.0.6
+      uses: Mattraks/delete-workflow-runs@<sha-of-v2.1> # v2.1

Pin to SHA for security (do not use the floating tag).

Side note

The v2.0.6 action logs lines prefixed with [dry-run] even when dry_run: false — this is a cosmetic labeling issue in that version of the action. Deletions are actually executed correctly (861 runs deleted in the run above). Worth verifying if v2.1 fixes this behavior.