Bump dbt-core from 1.4.5 to 1.6.15 in /plugins/flytekit-dbt

Bumps [dbt-core](https://github.com/dbt-labs/dbt-core) from 1.4.5 to 1.6.15.
- [Release notes](https://github.com/dbt-labs/dbt-core/releases)
- [Changelog](https://github.com/dbt-labs/dbt-core/blob/v1.6.15/CHANGELOG.md)
- [Commits](dbt-labs/dbt-core@v1.4.5...v1.6.15)

---
updated-dependencies:
- dependency-name: dbt-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

plugins/flytekit-dbt/dev-requirements.in

@@ -1,4 +1,4 @@
-dbt-core==1.4.5
+dbt-core==1.6.15
 dbt-sqlite==1.4.0
 dbt-semantic-interfaces<0.5.0
 numpy==1.26.4