Improved and fixed template for GPT-OSS (again). Includes preserve_thinking and fix for Unsloth-induced bug

An updated GPT-OSS template has been released, addressing a bug induced by Unsloth and incorporating a preserve_thinking feature. This new version refines the template previously updated a couple of months ago, specifically improving how assistant analysis and final content are rendered. The update also ensures that Chain-of-Thought (CoT) is dropped during previous turns, preventing its rendering for inference.