[FND-3] Release 7.0.0

[lucassus]

This pull request updates the Maxio Advanced Billing SDK documentation and introduces several improvements to the SDK's configuration and usability. The changes include updating the SDK version, enhancing documentation, and adding new features like proxy configuration support.

Documentation Updates:

• Updated all references from version 6.1.0 to 7.0.0 in the README.md and related documentation, including links to API controllers and authentication methods. [1] [2]
• Improved descriptions for API parameters, such as perPage and page, by adding clearer formatting and constraints. [1] [2]
• Enhanced the ApiException documentation to include its inheritance from PHP's Exception class and methods like getMessage() and getCode().

SDK Configuration Enhancements:

• Added support for proxy configurations via the ProxyConfigurationBuilder class, with updated documentation in doc/client.md.
• Updated the composer.json file to include the ext-curl dependency and upgraded the apimatic/unirest-php package to version 4.0.6.

Code and Script Improvements:

• Refactored the cleanupSite.sh script to improve readability and robustness by adding a shebang, enabling pipefail, and using consistent variable interpolation.

These changes collectively improve the SDK's functionality, make the documentation more user-friendly, and ensure compatibility with the latest SDK version.

[mykhi]

seems like everything auto generated with APIMATIC