feat(deps): remove the dotenv configurations for environment variables

[zimeg]

Type of change

• [ ] New sample
• [x] New feature
• [ ] Bug fix
• [ ] Documentation

Summary

This PR removes dotenv from the list of dependencies since the required environment variables SLACK_APP_TOKEN and SLACK_BOT_TOKEN are injected into the CLI run process on install.

Requirements

• [x] I’ve checked my submission against the Samples Checklist to ensure it complies with all standards
• [x] I have ensured the changes I am contributing align with existing patterns and have tested and linted my code
• [x] I've read and agree to the Code of Conduct

[zimeg]

@seratch sweet 🙌 Always open to reintroducing dotenv if other environment variables are needed in the future, but ready to merge this as is 🪓