DFG Viewer 6.3.0

It is the last release for version 6.x.

What's Changed

• [DEPENDENCY] Update Kitodo.Presentation to 5.1 by @beatrycze-volk in #337
• [FEATURE] Toggle metadata, toc and metadata subentries by @markusweigelt in #336
• [DEPENDENCY] Update versions for release 6.3 by @beatrycze-volk in #339

Full Changelog: v6.2.0...v6.3.0