chore: Update user-input.yml GitHub workflow to trigger on PR comments

[Annhiluc]

Description of the change

Update user-input.yml GitHub workflow to trigger additionally on PR comments.

Motivation

For easier triaging of open pull requests.

Type of change

Other

Checklist

• I have performed a self-review of my code.
• I have added detailed comments to my code where applicable.
• I have verified that my change does not break existing code.
• My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• I am familiar with the Google Style Guide for the language I have coded in.
• I have read through the Contributing Guide and signed the Contributor License Agreement.