enable Dependabot v2

[sullis]

Description

https://github.blog/2020-06-01-keep-all-your-packages-up-to-date-with-dependabot/

Related Issue

Types of changes

• Updated docs / Refactor code / Added a tests case / Automation (non-breaking change)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)