Add test to assert CHANGELOG format (#1582)

CHANGELOG.md

@@ -2,28 +2,25 @@
 
 ## NOT RELEASED
 
-### Changed
-
-- Allow passing explicit null values for optional fields of input objects
-
 ### Added
 
 - AWS api-change: Added `fips-us-gov-west-1` region
 
+### Changed
+
+- Allow passing explicit null values for optional fields of input objects
+
 ## 0.1.1
 
 ### Added
 
 - Avoid overriding the exception message with the raw message
+- AWS api-change: This release adds support for authenticating with Amazon Location Service's Places & Routes APIs with an API Key. Also, with this release developers can publish tracked device position updates to Amazon EventBridge.
 
 ### Changed
 
 - Improve parameter type and return type in phpdoc
 
-### Added
-
-- AWS api-change: This release adds support for authenticating with Amazon Location Service's Places & Routes APIs with an API Key. Also, with this release developers can publish tracked device position updates to Amazon EventBridge.
-
 ## 0.1.0
 
 First version