update union_relations to use core string literal macro

[dave-connors-3]

resolves #664

This is a:

• documentation update
• bug fix with no breaking changes
• new functionality
• a breaking change

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

Description & motivation

This updates the string_literal cross db macro in union_relations to use the core version rather than the dbt_utils version to avoid deprecation warnings.

Before

After

Checklist

• This code is associated with an Issue which has been triaged and accepted for development.
• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • BigQuery
  • Postgres
  • Redshift
  • Snowflake
• I followed guidelines to ensure that my changes will work on "non-core" adapters by:
  • dispatching any new macro(s) so non-core adapters can also use them (e.g. the star() source)
  • using the limit_zero() macro in place of the literal string: limit 0
  • using dbt.type_* macros instead of explicit datatypes (e.g. dbt.type_timestamp() instead of TIMESTAMP
• I have updated the README.md (if applicable)
• I have added tests & descriptions to my models (and macros if applicable)
• I have added an entry to CHANGELOG.md

[dbeatty10]

@dave-connors-3 I'm guessing that CI is failing because of this, but I don't know for certain.

[dave-connors-3]

@dbeatty10 have we noticed anything similar for other PRs?

[dbeatty10]

The main branch of dbt-bigquery is broken right now:

Since the CI for dbt-utils uses the main branch of dbt-bigquery, I'm guessing you'll need to wait for that to be fixed before re-running the tests for this PR.

[joellabes]

I approve the changes, but let's wait until BigQuery is passing to actually merge this in 👍

[dbeatty10]

This was the PR that got things passing again.

Should be good-to-go now.