Use nostr-ots without default feautres, avoid ureq dep

[RCasatta]

By providing a Stamper trait impl with the http library already in the dep tree

Description

I didn't like to add another HTTP dep to a library that already has one, with https://github.com/RCasatta/nostr-ots/pull/8 is possible to provide a Stamper trait to perform the needed HTTP request

Notes to the reviewers

The code is still a draft, but wanted to share the idea to receive early feedback

Changelog notice

Checklists

All Submissions:

• [x] I've signed all my commits
• [ ] I followed the contribution guidelines
• [ ] I ran make precommit before committing