fix: satisfy dim_model_7 contract in integration_tests_sl

The SL migration added a date_day time dimension to dim_model_7's YAML
but never projected the column in the SQL and never set its data_type.
Fusion's strict contract check fails on both counts. Emit a date literal
as date_day in the SELECT and declare `data_type: date` in the YAML.

Author: b-per

integration_tests_sl/models/marts/intermediate/_dim_model_7.yml

@@ -17,6 +17,7 @@ models:
         dimension:
           type: categorical
       - name: date_day
+        data_type: date
         dimension:
           type: time
         granularity: day

integration_tests_sl/models/marts/intermediate/dim_model_7.sql

@@ -6,4 +6,7 @@
 }}
 
 -- {{ ref('int_model_5') }}
-select * from {{ ref('stg_model_4') }}
+select
+    *,
+    cast('2024-01-01' as date) as date_day
+from {{ ref('stg_model_4') }}