Do not export changelog to source control

Seems we forgot to update this when we moved changelogs to a single file.

Author: driesvints

.gitattributes

@@ -14,7 +14,7 @@
 .gitattributes export-ignore
 .gitignore export-ignore
 .styleci.yml export-ignore
-CHANGELOG-* export-ignore
+CHANGELOG.md export-ignore
 CODE_OF_CONDUCT.md export-ignore
 CONTRIBUTING.md export-ignore
 docker-compose.yml export-ignore