docs(changelog): Add CHANGELOG entry for #315

Author: dbanty

CHANGELOG.md

@@ -23,6 +23,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Lowered the minimum version of `python-dateutil` to 2.8.0 for improved compatibility (#298 & #299). Thanks @bowenwr!
 - The `from_dict` method on generated models is now a `@classmethod` instead of `@staticmethod` (#215 & #292). Thanks @forest-benchling!
 
+### Fixes
+
+- The generated `from_dict` and `to_dict` methods of models will now properly handle `nullable` and `not required` properties that are themselves generated models (#315). Thanks @forest-benchling!
+
 ## 0.7.3 - 2020-12-21
 
 ### Fixes