Bump actions/cache from 3 to 4 (#45)

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...v4)

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

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

.github/workflows/docs-deploy.yml

@@ -21,7 +21,7 @@ jobs:
     # Note: This uses an internal pip API and may not always work
     # https://github.com/actions/cache/blob/master/examples.md#multiple-oss-in-a-workflow
     - name: Cache pip
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: ~/.cache/pip
         key: pip-${{ hashFiles('requirements.txt') }}