Improve version bump PR creation process

[flevi29]

Pull Request

I'm not entirely sure if this will run properly, we might only find out once it's merged.

Related issue

Fixes #1868

What does this PR do?

• adds manually dispatch-able workflow that creates PR with version bump
• make Release Drafter workflow update this open PR on additional release draft runs

PR checklist

Please check if your PR fulfills the following requirements:

• [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
• [x] Have you read the contributing guidelines?
• [x] Have you made sure that the title is accurate and descriptive of the changes?

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