chore: add pull request template

[andyesp]

Closes #1375

[1emu]

I like this checklist.

I would also add the following:

- [ ] **Security**
    - [ ] No sensitive data hardcoded
    - [ ] Proper input validation and sanitation (check routes and db queries)
    - [ ] Auth checks for new endpoints
- [ ] **Performance**
    - [ ] No N+1 queries
    - [ ] Proper use of caching/stale times
- [ ] **Rollback Plan**
    - [ ] Database migrations are reversible
    - [ ] Feature flags used for risky changes
- [ ] **Documentation**
    - [ ] README updated
    - [ ] Public API changes are documented (remove this one from Functionality Validation)
- [ ] **Accessibility**
    - [ ] UI changes are accessible, i.e., screen reader tests, Guane's magic check

Also, one important thing we are missing and we should add to one of this sections is the mobile view of any new page/component we add.
That could also be added to the Issue/Feature Checklist