ci(dependabot): add dependabot configuration

[aschaber1]

Hello,

really like your project :)

There are a few issues with outdated dependencies, I have created a depandabot.yml to support with automated dependency management.

Please also go to Settings -> Security -> Code security and analysis and Enable all three Dependabot sections:

• Dependabot alerts
• Dependabot security updates
• Dependabot version updates