Migrating from 5.5.0 to 5.5.1

Fixes and new features

• Fix MANIFEST.in to include katex.mjs.
• Remove extra / in include pattern (removes warning from django).

Backup database and files

BACKUP. YOUR. DATABASE. AND. FILES.

Update devilry to 5.5.1

Update the devilry version to 5.5.1 as described in Update Devilry.