Add auto merge dependabot workflow

[bdemann]

For Reviewers

Understanding the gh docs will help, especially the bit about merging

Contributor

• Breaking changes enumerated in the release issue
• New documentation enumerated in the release issue
• Code has been declaratized
• Error handling beautiful (no unwraps or expects etc)
• Code tested thoroughly
• All new functions have JSDoc/Rustdoc comments
• Related issues have been linked and all tasks have been completed or made into separate issues
• This PR's name is properly capitalized, descriptive, and ready to be in the release notes

Reviewer

• Breaking changes enumerated in the release issue
• New documentation enumerated in the release issue
• Code has been declaratized
• Error handling beautiful (no unwraps or expects etc)
• Code tested thoroughly
• All new functions have JSDoc/Rustdoc comments
• Related issues have been linked and all tasks have been completed or made into separate issues
• This PR's name is properly capitalized, descriptive, and ready to be in the release notes