Add dependabot.com to the repo to get updates of packages

[bravecobra]

Add dependabot.com to the repo to get updates of packages. Just a matter of registering for the service and the bot will create pull requests to this repo automatically when packages update to a ew version. That keeps this repo up to date.

[JuergenGutsch]

@bravecobra It seems you saw the ASP.NET Community Standup as well.
More details about dependabot: https://youtu.be/LiTUML8tG_Y