Update default python version for python models (#1273)

* update the default python version for python models; add a configuration file to collect future settings

Author: mikealfare

.changes/unreleased/Under the Hood-20241211-170831.yaml

@@ -0,0 +1,6 @@
+kind: Under the Hood
+body: Update default Python version for python models
+time: 2024-12-11T17:08:31.842063-05:00
+custom:
+  Author: mikealfare
+  Issue: "1203"

dbt/adapters/snowflake/constants.py

@@ -0,0 +1 @@
+DEFAULT_PYTHON_VERSION_FOR_PYTHON_MODELS = "3.9"

dbt/adapters/snowflake/impl.py

@@ -22,6 +22,7 @@
 from dbt_common.exceptions import CompilationError, DbtDatabaseError, DbtRuntimeError
 from dbt_common.utils import filter_null_values
 
+from dbt.adapters.snowflake import constants
 from dbt.adapters.snowflake.relation_configs import (
     SnowflakeRelationType,
     TableFormat,
@@ -345,7 +346,9 @@ def submit_python_job(self, parsed_model: dict, compiled_code: str):
         schema = parsed_model["schema"]
         database = parsed_model["database"]
         identifier = parsed_model["alias"]
-        python_version = parsed_model["config"].get("python_version", "3.8")
+        python_version = parsed_model["config"].get(
+            "python_version", constants.DEFAULT_PYTHON_VERSION_FOR_PYTHON_MODELS
+        )
 
         packages = parsed_model["config"].get("packages", [])
         imports = parsed_model["config"].get("imports", [])