API cannot handle tags containing slashes

[marcelklehr]

Steps to reproduce

1. Create a bookmark and add a tag with a slash in the middle
2. Try to delete the tag via the API

Expected behaviour

The tag should be deleted

Actual behaviour

The server returns a 404, because the slash, even though urlencoded, is interpreted as a path seperator

Server configuration

Web server: Apache

Nextcloud version: 13