docs(contributing): update contributing.md for get started instructions

[tintayadev]

Resolves(#13)

Pull Request description

Since the guide to start contributing was outdated and skipped some needed information, the contributing.md file has been updated. Now, it includes the full guide to set the development environment. And so, ensuring that new contributors can easily understand how to get started.

The following steps were added:

• Miniforge requirement
• Use mamba when creating the environment with conda
• Installation of dependencies with poetry
• Github token generation
• Run tests

How to test these changes

• ...

Pull Request checklists

This PR is a:

• bug-fix
• new feature
• maintenance

About this PR:

• it includes tests.
• the tests are executed on CI.
• the tests generate log file(s) (path).
• pre-commit hooks were executed locally.
• this PR requires a project documentation update.

Author's checklist:

• I have reviewed the changes and it contains no misspelling.
• The code is well commented, especially in the parts that contain more complexity.
• New and old tests passed locally.

Additional information

Reviewer's checklist

Copy and paste this template for your review's note:

## Reviewer's Checklist

- [ ] I managed to reproduce the problem locally from the `main` branch
- [ ] I managed to test the new changes locally
- [ ] I confirm that the issues mentioned were fixed/resolved .

[xmnlab]

LGTM! thanks @tintayadev !