Release 4.3 - Kotlin extensions and support for suspending continuations

This release introduces the following new features and fixes:

• Added Kotlin extensions, such as the .l property, which can be used to close tags in Kotlin instead of .__().
• Introduced a new .suspending() builder to support the use of continuations in Kotlin, allowing suspending functions to use await.
• Resolved Issue 105 by integrating new attributes in globalEventAttributes, included with the release of HtmlApiFaster 1.0.15.
• Added new unit tests verifying multi-threaded scenarios.
• Updated the documentation to detail setIndentation() usage and the correct application of threadSafe().