Update PULL_REQUEST_TEMPLATE.md

[seabbs]

Description

Updates proposed title for PRs in the PR template

Checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have included the target issue or issues in the PR title in the for Issue(s) #issue-number: PR title
• I have read the contribution guidelines.
• I have tested my changes locally.
• I have updated the documentation if required.
• My code follows the established coding standards.
• I have added a news item linked to this PR.
• I have updated the package development version by one increment in both NEWS.md and the DESCRIPTION.
• I have reviewed CI checks for this PR and addressed them as far as I am able.