chore(exllama): drop backend now almost deprecated (#8186)

exllama2 development has stalled and only old architectures are
supported. exllamav3 is still in development, meanwhile cleaning up
exllama2 from the gallery.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

backend/python/README.md

@@ -16,7 +16,6 @@ The Python backends use a unified build system based on `libbackend.sh` that pro
 - **transformers** - Hugging Face Transformers framework (PyTorch-based)
 - **vllm** - High-performance LLM inference engine
 - **mlx** - Apple Silicon optimized ML framework
-- **exllama2** - ExLlama2 quantized models
 
 ### Audio & Speech
 - **bark** - Text-to-speech synthesis