Adding dotenv support

[i-wagner]

Description

Currently, Snowflake-manager requires secrets (Snowflake credentials) to be stored in the system's environment variables (e.g., .bash_profile). So, if working with different setups that require different credentials, the user had to comment out credentials, whenever switching between setups.

Changes

• Added support for dotenv files to store secrets project-wise
• Changed how the Snowflake cursor is set up in inspector.py: If the Snowflake credentials are not stored as part of the system's environment variables, the previous cursor definition resulted in an exception, because it tried to connect to Snowflake, in absence of valid credentials

Checklist

• My pull request represents one logical piece of work
• My commits are related to the pull request and look clean
• I tested my changes locally with pytest -vv
• I formatted my code with black .

[lpillmann]

Looks very good to me!

I like how you also refactored the use of cursors with a context manager instead 👍

Both the implementation and documentation are clear. I left two very minor suggestions that are optional.

Congrats on the first PR here 🎉