Bump CSSUoB/pr-auto-updater from 2.1.2 to 2.2.1 in the gh-actions group (#40)

Bumps the gh-actions group with 1 update: [CSSUoB/pr-auto-updater](https://github.com/cssuob/pr-auto-updater).


Updates `CSSUoB/pr-auto-updater` from 2.1.2 to 2.2.1
- [Release notes](https://github.com/cssuob/pr-auto-updater/releases)
- [Commits](v2.1.2...v2.2.1)

---
updated-dependencies:
- dependency-name: CSSUoB/pr-auto-updater
  dependency-version: 2.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: gh-actions
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/autoupdate.yaml

@@ -10,7 +10,7 @@ jobs:
       pull-requests: write
       contents: write
     steps:
-      - uses: CSSUoB/pr-auto-updater@v2.1.2
+      - uses: CSSUoB/pr-auto-updater@v2.2.1
         env:
           GITHUB_TOKEN: '${{ secrets.PR_AUTO_UPDATE_TOKEN }}'
           PR_FILTER: 'labelled'