Fix Markdown headings

CHANGELOG.md

@@ -3,7 +3,7 @@
 Records breaking changes from major version bumps
 
 
-## 44.0.0
+## 44.0.0
 
 PR [#455](https://github.com/alphagov/digitalmarketplace-utils/pull/455)
 
@@ -30,7 +30,7 @@ dm_mandrill now contains a single class `DMMandrillClient`
 `dm_mandrill.get_sent_emails` has been deleted. Its functionality has been moved to `DMMandrillClient.get_sent_emails`, however the function signature has changed.
 
 
-## 43.0.0
+## 43.0.0
 
 PR [#447](https://github.com/alphagov/digitalmarketplace-utils/pull/447)
 
@@ -47,7 +47,7 @@ initialization of FeatureFlags for the app.
 The dependency on Flask has been upgraded to Flask 0.12, so potentially apps are going to have to make changes
 in concordance with http://flask.pocoo.org/docs/0.12/changelog/
 
-## 42.0.0
+## 42.0.0
 
 PR [#400](https://github.com/alphagov/digitalmarketplace-utils/pull/400)