Add workflow Dependabot PR -> Linear issue

[havardholvik]

Description

Adds workflow which checks if a PR is opened by dependabot and creates Linear issue for timely handling of the proposed change.

Testing

Nothing to test, will take into effect on the next PR opened by Dependabot

Checklist

• My code follows the project's coding standards.
• I have written unit tests (if applicable).
• I have updated the documentation (if applicable).
• By submitting this pull request, I confirm that my contribution is made
  under the terms of the MIT license.

[nandito]

You can run a lint or prettier fix on the file to use 4 spaces instead of 2. But I don't mind merging it as is. Worflow definitions are probably excluded from the linter/prettier.