Allow a list of skippable authors

[Tim Pillinger (wxtim)]

Default to include dependabot

PR Summary

closes 83 - allow user to skip CLA verification for some user names, to allow for merge of dependabot branches.

Code Reviewer:

Code Quality Checklist

(Some checks are automatically carried out via the CI pipeline)

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• The modified workflow's README has been updated, if required
• The changes have been sufficiently tested (please describe)

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance
  of Generative AI tool name (e.g., Met Office Github Copilot Enterprise,
  Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the
  Simulation Systems AI policy
  (including attribution labels)

Natural Stupidity only in my PR's

Code Review

• The changes are appropriate and testing has been sufficient

[Tim Pillinger (wxtim)]

I'd appreciate any help I can get testing this.