[py] PaLM Model Parser doesn't check for API Key

[Ankush-lastmile]

PaLM model parser doesn't explicitly check for API key.

It currently needs to be manually configured by doing something like the following

import google.generativeai as palm
import os
palm.configure(api_key=os.getenv("PALM_KEY"))   

In this example the key must be an environment variable under the name "PALM_KEY"

[Ankush-lastmile]

note: without an api key check, palm api throws an unrecognizable error.