v1.4.8rc4

## Import Notes

**Refactoring Prompt Template and enhancing robust mal-format handling for Knowledge Graph (KG) extraction using Small Parameter Language Models (LLMs). This will invalidate all cached LLM outputs.**

## What's Changed

* Fix: Eliminate Lambda Closure Bug in Embedding Function Creation by @avchauzov in https://github.com/HKUDS/LightRAG/pull/2028
* refac: Eliminate Conditional Imports and Simplify Initialization by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2029
* Fix: Preserve Leading Spaces in Graph Label Selection by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2030
* Fix ENTITY_TYPES Environment Variable Handling by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2034
* refac: Enhanced Entity Relation Extraction Text Sanitization and Normalization by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2031
* refact: Enhance KG Extraction with Improved Prompts and Parser Robustness by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2032
* Fix LLM output instability for <|> tuple delimiter by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2035
* Enhance KG Extraction for LLM with Small Parameters by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2051
* Add VDB error handling with retries for data consistency by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2055
* Fix incorrect variable name in NetworkXStorage file path by @danielaskdd in https://github.com/HKUDS/LightRAG/pull/2060

## New Contributors

* @avchauzov made their first contribution in https://github.com/HKUDS/LightRAG/pull/2028

**Full Changelog**: https://github.com/HKUDS/LightRAG/compare/v1.4.7...v1.4.8rc2