Update dependabot-auto-merge.yml

[thejmitchener]

Pull Request Description

This pull request updates the dependabot-auto-merge.yml configuration to enhance the automation of our dependency management process.

Motivation:

By adding the workflow_dispatch event, we allow for manual triggering of the auto-merge workflow in addition to the existing functionality that responds to pull_request_target events. This flexibility enables maintainers to initiate dependency updates at their discretion, ensuring that we can manage updates more effectively according to our development schedule and priorities.

Improvements:

1. Increased Flexibility: Maintainers can now manually trigger the auto-merge workflow, providing better control over when dependencies are updated.
2. Enhanced Workflow Management: This change allows for a more responsive approach to handling dependencies, which is crucial for maintaining project stability and security.

Overall, this update improves our dependency management process, ensuring that we can keep our project up-to-date with minimal disruption.