docs: correct v0.9.0 release date (#158)

Author: ewanharris

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 ## v0.9.0
 
-### [0.9.0](https://github.com/openfga/python-sdk/compare/v0.8.1...v0.9.0) (2024-12-18)
+### [0.9.0](https://github.com/openfga/python-sdk/compare/v0.8.1...v0.9.0) (2024-12-19)
 
 - feat: remove client-side validation - thanks @GMorris-professional (#155)
 - feat: add support for `start_time` parameter in `ReadChanges` endpoint (#156) - Note, this feature requires v1.8.0 of OpenFGA or newer