CHANGELOG.md in open_api-0.3.0 vs CHANGELOG.md in open_api-0.3.1

@@ -1,4 +1,7 @@
+## 0.3.1
+* Keep hash keys to be string
+
 ## 0.3.0
 * Add `#serializable_hash` to Components
 * Allow Paths and Responses to set like a hash
 * Fallback to string when it has no serializable way