v.0.2.6

This release includes additional stability and performance improvements. In addition, excited to support [custom retrievers](https://docs.gptr.dev/docs/gpt-researcher/retrievers#custom-retrievers) - Custom retrievers allow you to use any search engine that provides an API to retrieve documents and is widely used for enterprise research tasks. Thanks again to the amazing community for all the contributions!

## What's Changed
* change deployment name to model to fix the init of the azureopenai model by @xiepei1 in https://github.com/assafelovic/gpt-researcher/pull/594
* use repair_json() on output of sub_queries to stop exceptions on local models by @pfrench42 in https://github.com/assafelovic/gpt-researcher/pull/596
* fix: similarity_threshold config by @gkhngyk in https://github.com/assafelovic/gpt-researcher/pull/597
* Lazily import langchain-huggingface to avoid obligatory install by @ldorigo in https://github.com/assafelovic/gpt-researcher/pull/599
* added implementation for custom retriever by @assafelovic in https://github.com/assafelovic/gpt-researcher/pull/602

## New Contributors
* @xiepei1 made their first contribution in https://github.com/assafelovic/gpt-researcher/pull/594
* @pfrench42 made their first contribution in https://github.com/assafelovic/gpt-researcher/pull/596

**Full Changelog**: https://github.com/assafelovic/gpt-researcher/compare/v.0.2.5...v.0.2.6