Bump actions/deploy-pages from 1 to 2

Bumps [actions/deploy-pages](https://github.com/actions/deploy-pages) from 1 to 2.
- [Release notes](https://github.com/actions/deploy-pages/releases)
- [Commits](https://github.com/actions/deploy-pages/compare/v1...v2)

---
updated-dependencies:
- dependency-name: actions/deploy-pages
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/marp-pages.yml

@@ -44,4 +44,4 @@ jobs:
           path: 'build'
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v1
+        uses: actions/deploy-pages@v2