:sparkles: Recognize scala-steward as dependency update tool

[raboof]

What kind of change does this PR introduce?

Recognize scala-steward as dependency update tool

• [x] PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

Repositories that are configured to use scala-steward score '0' on the 'Dependency-Update-Tool' check

What is the new behavior (if this is a feature change)?**

Repositories that are configured to use scala-steward score '10' on the 'Dependency-Update-Tool' check

• [x] Tests for the changes have been added (for bug fixes/features)

Which issue(s) this PR fixes

NONE

Special notes for your reviewer

Does this PR introduce a user-facing change?

For user-facing changes, please add a concise, human-readable release note to the release-note

(In particular, describe what changes users might need to make in their application as a result of this pull request.)

Recognize scala-steward as dependency update tool

[spencerschrock]

Thanks!