add qwant.com in blockable search engines

[hayo]

Description

would be nice to add this search engine. I'm having some difficulties adding it as a custom serp.

Checklist

• I have searched existing discussions and issues to ensure this idea hasn't been suggested before
• I'm willing to help implement this feature (write code, test, etc.)

[fadam-csgroup]

Support has been removed in https://github.com/iorate/ublacklist/releases/tag/v9.0.0

It seems that it is possible to add it following #573 (comment)