Update epubcheck-ruby requirement from 5.2.0.0 to 5.2.1.0 (#72) Updates the requirements on [epubcheck-ruby](https://github.com/takahashim/epubcheck-ruby) to permit the latest version. - [Commits](https://github.com/takahashim/epubcheck-ruby/compare/v5.2.0.0...v5.2.1.0) --- updated-dependencies: - dependency-name: epubcheck-ruby dependency-type: direct:production ... Signed-off-by: dependabot[bot] <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>