build: add workflow to automatically create release PRs

[StephenHulme]

Follows on from https://github.com/sanger/limber/pull/1930 to implement the same process in Sequencescape.

The result would look like: https://github.com/sanger/.github/pull/16

Changes proposed in this pull request

• Automatically create merge-to-master PR when commits are pushed to develop
• Add additional trigger to Release Version Check when master PRs are marked as ready-for-review

Instructions for Reviewers

[All PRs] - Confirm PR template filled
[Feature Branches] - Review code
[Production Merges to main]
    - Check story numbers included
    - Check for debug code
    - Check version