Migrate to hugo mods - Githubissues

Describe your changes

Migration to use hugo mods instead of git submodules for themes. Result is that search function is working again.

[ ] I have performed a self-review of my code
[ ] If it is a core feature, I have added thorough tests.
[ ] Do we need to implement analytics?
[ ] Will this be part of a product update? If yes, please write one phrase about this update.