🔧 change default demo user email

I verified my work is based on develop branch

• yes, keep going
• hum... no, because:
  • I don't understand the develop / branch / trees / flowers stuff !
  • I need help. No worries, we will help you :)
  • I'm a super-karma-powered contributor, will not tick this box and will rebase my PR within seconds (thanks :) )

Purpose of this Pull Request?

Where should the reviewer start its review?

How the PR could be tested?

Any background context you want to provide?

What are the related issues?

Screenshots (if appropriate)

(by the way, thank you very much for contributing to Asqatasun!)

Closes #267 (closed)