build(deps): bump actionpack-page_caching from 1.1.1 to 1.2.1

Bumps [actionpack-page_caching](https://github.com/rails/actionpack-page_caching) from 1.1.1 to 1.2.1.
- [Release notes](https://github.com/rails/actionpack-page_caching/releases)
- [Changelog](https://github.com/rails/actionpack-page_caching/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/actionpack-page_caching/compare/v1.1.1...v1.2.1

)

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