Remove unused variables

[pnijhara]

Find the other issues found here - https://deepsource.io/gh/pnijhara/alpha_vantage/issues/?category=recommended

This PR also adds .deepsource.toml configuration file to run DeepSource analysis on the repo with. Upon enabling DeepSource, the analysis will run on every PR and commit to detect 560+ types of issues in the changes — including bug risks, anti-patterns, security vulnerabilities, etc.

To enable DeepSource analysis after merging this PR, please follow these steps:

1. Signup on DeepSource with your GitHub account and grant access to this repo.
2. Activate analysis on this repo here.

You can also look at the docs for more details. Do let me know if I can be of any help!

[PatrickAlphaC]

Thanks for this PR! What advantage would this deepsource have over pep8 or just updated github actions? Is this a new technology? This is the first I've seen of it. Would love to try it out if it's reliable. Looks like it has caught a few good bugs in here.

[pnijhara]

DeepSource is a static analysis tool natively integrated with GitHub/GitLab code review workflows. The Python analyzer catches not only the style issues ( code violating PEP8 guidelines ) but detects issues which can compromise security and performance, anti-patterns, type-check issues, potential bug-risks, test-coverage issues etc.
The service is completely free to use for open-source and is reliable. Behind the scenes, the analyzer catches these issues by looking for patterns in the AST of the code. You should give it a try.