[CT-1017] No module named 'pandas' for python models

[ChenyuLInx]

Describe the bug

when running dbt python models on snowflake without using pandas, dbt will throw an error

13:09:39    ModuleNotFoundError: No module named 'pandas'
13:09:39     in function PYTHON_MODEL__DBT_SP with handler main

This is because in materialization code we use pandas to determine whether the returned dataframe is a snowpark dataframe or a pandas dataframe, and do slightly different things based on that

Steps To Reproduce

Run a python model without specify pandas as part of the package

Expected behavior

Everything works just fine.

Solution

Always add pandas as the required dependencies.
This means each user will have to agree the anaconda policy on snowflake.

Other comment

one really odd thing is that we have a basic python model test(written in core, inhereted in dbt-snowflake) that run things in this way on our testing snowflake account, and doesn't run into the same issue. maybe we added pandas as a global library there?