* update URLs from stainlessapi.com to stainless.com ([305](https://github.com/RetellAI/retell-python-sdk/issues/305)) ([f37bd78](https://github.com/RetellAI/retell-python-sdk/commit/f37bd78982c188dc079665c77ac56b0489515df4))
4.20.0
Full Changelog: [v4.19.0...v4.20.0](https://github.com/RetellAI/retell-python-sdk/compare/v4.19.0...v4.20.0)
Features
* **api:** api update ([290](https://github.com/RetellAI/retell-python-sdk/issues/290)) ([7a9f3b6](https://github.com/RetellAI/retell-python-sdk/commit/7a9f3b671fd706481bee7bfb93b22e928a572168)) * **api:** api update ([293](https://github.com/RetellAI/retell-python-sdk/issues/293)) ([b44b4a7](https://github.com/RetellAI/retell-python-sdk/commit/b44b4a7c60bd36356215d3d65c6a2c6b53d72da5)) * **api:** api update ([295](https://github.com/RetellAI/retell-python-sdk/issues/295)) ([517cb44](https://github.com/RetellAI/retell-python-sdk/commit/517cb446dd3bbbee5b135e9d2de3b914989890ca)) * **api:** api update ([296](https://github.com/RetellAI/retell-python-sdk/issues/296)) ([0275240](https://github.com/RetellAI/retell-python-sdk/commit/02752405df39ae7129419093e1a1307d891bb379)) * **api:** api update ([299](https://github.com/RetellAI/retell-python-sdk/issues/299)) ([b4a62b6](https://github.com/RetellAI/retell-python-sdk/commit/b4a62b6d28e9865d1be7b19c6e6f0ef6750318b2)) * **api:** api update ([300](https://github.com/RetellAI/retell-python-sdk/issues/300)) ([5848752](https://github.com/RetellAI/retell-python-sdk/commit/584875228384879978b1f164a88efbd25ea440b8)) * **client:** allow passing `NotGiven` for body ([297](https://github.com/RetellAI/retell-python-sdk/issues/297)) ([4ee0ba9](https://github.com/RetellAI/retell-python-sdk/commit/4ee0ba9ed6438cf540c6280372eeefdadba91003))
Bug Fixes
* asyncify on non-asyncio runtimes ([294](https://github.com/RetellAI/retell-python-sdk/issues/294)) ([0808f3f](https://github.com/RetellAI/retell-python-sdk/commit/0808f3f8223ca559b42f6ec3b3aab6db41ee00dc)) * **client:** mark some request bodies as optional ([4ee0ba9](https://github.com/RetellAI/retell-python-sdk/commit/4ee0ba9ed6438cf540c6280372eeefdadba91003))