docs: fix version in changelog

Author: macintoshpie

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## Version 2.3.1
 
-BuildingSync Version 2.2.1 does not introduce any breaking changes. Version 2.2.1's only change is the `schemaLocation`
+BuildingSync Version 2.3.1 does not introduce any breaking changes. Version 2.3.1's only change is the `schemaLocation`
 for the gbXML Schema v6.01. The new `schemaLocation` points to [BuildingSync's mirror of the schema](https://github.com/BuildingSync/gbXML_Schemas/releases/tag/v6.01). See [issue #393](https://github.com/BuildingSync/schema/issues/393) for more information.
 
 ## Version 2.3.0