docs: fix changelog header to consistent size (#116)

Co-authored-by: Anthonios Partheniou <partheniou@google.com>

packages/google-cloud-apigee-connect/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-### [1.3.1](https://github.com/googleapis/python-apigee-connect/compare/v1.3.0...v1.3.1) (2022-03-05)
+## [1.3.1](https://github.com/googleapis/python-apigee-connect/compare/v1.3.0...v1.3.1) (2022-03-05)
 
 
 ### Bug Fixes
@@ -24,7 +24,7 @@
 
 * add autogenerated code snippets ([86b45c2](https://github.com/googleapis/python-apigee-connect/commit/86b45c2379df54b274d192e5a46e6348e4f86005))
 
-### [1.2.1](https://www.github.com/googleapis/python-apigee-connect/compare/v1.2.0...v1.2.1) (2021-11-01)
+## [1.2.1](https://www.github.com/googleapis/python-apigee-connect/compare/v1.2.0...v1.2.1) (2021-11-01)
 
 
 ### Bug Fixes
@@ -51,14 +51,14 @@
 
 * add context manager support in client ([#54](https://www.github.com/googleapis/python-apigee-connect/issues/54)) ([0dc1edd](https://www.github.com/googleapis/python-apigee-connect/commit/0dc1eddc5fae79b2516789587eb097190c8f1420))
 
-### [1.0.2](https://www.github.com/googleapis/python-apigee-connect/compare/v1.0.1...v1.0.2) (2021-09-30)
+## [1.0.2](https://www.github.com/googleapis/python-apigee-connect/compare/v1.0.1...v1.0.2) (2021-09-30)
 
 
 ### Bug Fixes
 
 * improper types in pagers generation ([fb8b837](https://www.github.com/googleapis/python-apigee-connect/commit/fb8b837d64c9771d7af9d36688e00243794ea731))
 
-### [1.0.1](https://www.github.com/googleapis/python-apigee-connect/compare/v1.0.0...v1.0.1) (2021-09-24)
+## [1.0.1](https://www.github.com/googleapis/python-apigee-connect/compare/v1.0.0...v1.0.1) (2021-09-24)
 
 
 ### Bug Fixes
@@ -73,7 +73,7 @@
 
 * bump release level to production/stable ([#28](https://www.github.com/googleapis/python-apigee-connect/issues/28)) ([65803db](https://www.github.com/googleapis/python-apigee-connect/commit/65803db4821b594124bfb88012ba4f954568a895))
 
-### [0.2.2](https://www.github.com/googleapis/python-apigee-connect/compare/v0.2.1...v0.2.2) (2021-07-29)
+## [0.2.2](https://www.github.com/googleapis/python-apigee-connect/compare/v0.2.1...v0.2.2) (2021-07-29)
 
 
 ### Bug Fixes
@@ -90,7 +90,7 @@
 
 * release as 0.2.2 ([#25](https://www.github.com/googleapis/python-apigee-connect/issues/25)) ([f6660d3](https://www.github.com/googleapis/python-apigee-connect/commit/f6660d3d604c61b748abe59a51923b74b687d761))
 
-### [0.2.1](https://www.github.com/googleapis/python-apigee-connect/compare/v0.2.0...v0.2.1) (2021-07-21)
+## [0.2.1](https://www.github.com/googleapis/python-apigee-connect/compare/v0.2.0...v0.2.1) (2021-07-21)
 
 
 ### Bug Fixes