Create Dependabot config file

[dependabot-preview]

👋 Dependabot is moving natively into GitHub! This pull request migrates your configuration from Dependabot.com to a config file, using the new syntax. When you merge this pull request, we'll swap out dependabot-preview (me) for a new dependabot app, and you'll be all set!

With this change, you'll now use the Dependabot page in GitHub, rather than the Dependabot dashboard, to monitor your version updates. Dependabot is now configured exclusively using config files.

You have configured automerging on this repository. There is no automerging support in GitHub-native Dependabot, so these settings will not be added to the new config file. Several 3rd-party GitHub Actions and bots can replicate the automerge feature.

If you've got any questions or feedback for us, please let us know by creating an issue in the dependabot/dependabot-core repository.

Learn more about the relaunch of Dependabot

Please note that regular @dependabot commands do not work on this pull request.

🤖💛

[richlander]

FYI: I'm disabling dependabot-preview for the dotnet org. This PR will move the repo to the new system.

[clairernovotny]

We rely on auto merge and the new version doesn't do that at present.

[dependabot-preview]

As a reminder, Dependabot Preview will be shut down on August 3rd, 2021. You can merge this pull request to migrate to GitHub-native Dependabot. You can read the docs to learn more about what's changing, as well as find out how to get support if you need help migrating.

[bartdesmet]

@richlander @clairernovotny please advise on the course of action for this PR given that the original Dependabot has been shut down. I've spent some time earlier today to clean up remnants of failed auto-merges (with one remaining around broken Xunit code), so all of the original bot's PRs will be merged by EOD.

[clairernovotny]

I just merged it; there's no solution to add specific dependencies to an allow-list for auto merge sadly.