fix: update changelog

Author: Luca Kiedrowski

CHANGELOG.md

@@ -12,7 +12,7 @@ typos, schema fixes, or adding examples.
 
 ### [3.1.0] - 2024-06-13
 ### Changed
-* `/v2/usage`: Now returns a detailed response for API Pro users, including per-product usage and billing period information. For API Free and Pro Classic users, the response remains unchanged and only includes `character_count` and `character_limit`. Both response types are documented in the OpenAPI spec using `oneOf`.
+* `/v2/usage`: Now returns a detailed response for API Pro users, including per-product usage and billing period information. For API Free and Pro Classic users, the response remains unchanged and only includes `character_count` and `character_limit`.
 
 
 ### [3.0.2] - 2025-04-24