fix: set severity to warn for compound column uniqueness expectation (#2240)

Author: rachellougee

src/ol_dbt/models/intermediate/mitxonline/_int_mitxonline__models.yml

@@ -868,6 +868,9 @@ models:
   - dbt_expectations.expect_compound_columns_to_be_unique:
       arguments:
         column_list: ["user_id", "courserun_id", "mitxonline_program_id"]
+        config:
+          severity: warn
+
 - name: int__mitxonline__programenrollments
   description: Intermediate model of enrollments in MITx Online.
   columns: