Bump purcell/setup-emacs from 6.0 to 7.0 (#23)

Bumps [purcell/setup-emacs](https://github.com/purcell/setup-emacs) from 6.0 to 7.0.
- [Release notes](https://github.com/purcell/setup-emacs/releases)
- [Commits](purcell/setup-emacs@v6.0...v7.0)

---
updated-dependencies:
- dependency-name: purcell/setup-emacs
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/jekyll.yml

@@ -23,7 +23,7 @@ jobs:
         with:
           ruby-version: '3.1'
       - name: Setup Emacs
-        uses: purcell/setup-emacs@v6.0
+        uses: purcell/setup-emacs@v7.0
         with:
           version: 28.1
       - name: Run Emacs Org mode publish to convert Org mode files to HTML