Make beautifulsoup4 an Optional Dependency

[Lukas-solar]

Make beautifulsoup4 an Optional Dependency

Summary

This PR moves beautifulsoup4 to an optional dependency, installable via the html extra:

pip install atlassian-python-api[html]

Rationale

• Limited Usage Scope: beautifulsoup4 is only required for HTML parsing in a small subset of modules. The majority of the package's functionality does not depend on it.
• Reduces Installation Overhead: By not enforcing installation of unused dependencies, we streamline the installation process for users who don't need HTML parsing.
• Improves Compatibility: Some environments (e.g., minimal Docker images or serverless functions) may benefit from fewer dependencies, faster builds, and smaller footprints.
• Design Philosophy: Since HTML parsing can be seen as a less "clean" or ideal approach (often used as a workaround when APIs or structured data aren't available), it's appropriate to isolate this functionality and not impose it on all users by default.

Usage Note

If a user requires HTML-related features, they can explicitly install the optional dependency.
Attempting to use the HTML-parsing functionality without installing beautifulsoup4 will raise an informative ImportError.

[gonchik]

@Lukas-solar Thank you! Indeed that very good step.

Let's try to deploy it