Allow specifying a tag to add to PRs

[martinklepsch]

Feature Request

Problem Statement

When working with lots of PRs it's helpful to filter by tags. Dependabot adds a tag dependencies to all PRs it creates. This allows only viewing dependency upgrades but also hiding them if wanted.

Personally I often want to hide dependency upgrade PRs when looking for PRs to review.

Ideal Solution

Provide an additional option to the action that allows specifying a tag that is added to PRs