Fix typo in dbt-core install script

Author: mkrahu-z2

.github/workflows/dbt_v1.10.15_snowflake_build_full_refresh.yml

@@ -44,7 +44,7 @@ jobs:
       - name: Install dbt
         run: |
           python -m pip install --upgrade pip
-          pip install dbt-core=${{ env.DBT_CORE_VERSION }} dbt-snowflake
+          pip install dbt-core==${{ env.DBT_CORE_VERSION }} dbt-snowflake
 
       - name: Install dbt dependencies
         working-directory: ${{ env.DBT_PROJECT_DIR }}