add how to test section to PR template

[dcmcand]

No Issue

Description

This pull request:

• adds a How to Test section to the PR template

Pull request checklist

• [ ] Did you test this change locally?
• [ ] Did you update the documentation (if required)?
• [ ] Did you add/update relevant tests for this change (if required)?

Additional information

How to test

This is the test. It seems to work :D

[netlify[bot]]

✅ Deploy Preview for kaleidoscopic-dango-0cf31d canceled.

Name	Link
🔨 Latest commit	ff813fce76b9b9f129fd76bc98831c19cc0004a5
🔍 Latest deploy log	https://app.netlify.com/sites/kaleidoscopic-dango-0cf31d/deploys/65b02e4e5c80d40008e093a9