fix(changelog): strict rules

CHANGELOG.md

@@ -5,13 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project will adhere to [Semantic Versioning](https://semver.org/spec/v2.0.0.html) once it reaches maturity in v1.
 
-## [] - Unreleased
-
-### Added
-
-### Changed
-
-### Fixed
+## [Unreleased]
 
 ## [0.1.33] - 2021-11-24
 
@@ -20,8 +14,6 @@ and this project will adhere to [Semantic Versioning](https://semver.org/spec/v2
 - `/addresses/{address}/extended` endpoint
 - `/accounts/{stake_address}/addresses/total` endpoint
 
-### Changed
-
 ### Fixed
 
 - multiple descriptions
@@ -32,10 +24,6 @@ and this project will adhere to [Semantic Versioning](https://semver.org/spec/v2
 
 - `block_time` property to `/assets/{asset}/transactions`
 
-### Changed
-
-### Fixed
-
 ## [0.1.31] - 2021-10-30
 
 ### Added