test-warehouse: pin on version 30 for now

Author: haritamar

.github/workflows/test-warehouse.yml

@@ -134,6 +134,7 @@ jobs:
         if: inputs.dbt-version == 'fusion'
         run: |
           curl -fsSL https://public.cdn.getdbt.com/fs/install/install.sh | sh -s -- --update
+          ~/.local/bin/dbt system update --version 2.0.0-preview.30
 
       - name: Install Elementary
         run: pip install "./elementary[${{ (inputs.warehouse-type == 'databricks_catalog' && 'databricks') || inputs.warehouse-type }}]"