update tests: -> data_tests:

[graciegoheen]

resolves #894

This is a:

• just an update to the integration_tests (non-breaking change)

All pull requests from community contributors should target the main branch (default).

Description & motivation

With the new dbt-core v1.8, the syntax for data tests have updated from tests: to data_tests:. This PR updates that syntax to get rid of the warning message.

Checklist

• This code is associated with an Issue which has been triaged and accepted for development.