fix: Fixes validator field access for 'project_id' in BigQuery offlin…

…e Store (#4509)

Fixes validator field access for 'billing_project_id' in BigQuery Offline Store

Signed-off-by: gesche <26026582+jgesche@users.noreply.github.com>

sdk/python/feast/infra/offline_stores/bigquery.py

@@ -114,7 +114,7 @@ class BigQueryOfflineStoreConfig(FeastConfigBaseModel):
 
     @field_validator("billing_project_id")
     def project_id_exists(cls, v, values, **kwargs):
-        if v and not values["project_id"]:
+        if v and not values.data["project_id"]:
             raise ValueError(
                 "please specify project_id if billing_project_id is specified"
             )