review semantics, implementation, and testing of methods in utils package

[adampingel]

The utils.get_env_vars() function has the side-effect of setting the given variable in the environment. This is due to the fact that the Replicate client is not passing the api key through to later stages of processing. We would like to remove the side-effect.

Options:

• Use set_env_var(get_env_var('VAR')) to set the variable before using the replicate client.
• Fix the replicate client (contrib to langchain-community) to pass the api key through.

[adampingel]

See discussion in #19

[fayvor]

See this issue for ways to get Replicate API Key to pass through.