Add automatic changelog generation

As part of what we discussed on gitlab-com/gl-infra&193 (closed) this MR implements changelog automation

$ _support/generate_changelog 8.31.0
$ git diff

diff --git a/CHANGELOG b/CHANGELOG
index 80426a6..e0e2342 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,12 @@
 
 Formerly known as 'gitlab-git-http-server'.
 
+## v8.31.0
+
+### Other
+- Add automatic changelog generation
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/484
+
 v 8.30.0
 
 - Proxy ActionCable websocket connection !454
diff --git a/changelogs/unreleased/changelog-generator.yml b/changelogs/unreleased/changelog-generator.yml
deleted file mode 100644
index 198ccc7..0000000
--- a/changelogs/unreleased/changelog-generator.yml
+++ /dev/null
@@ -1,5 +0,0 @@
----
-title: Add automatic changelog generation
-merge_request: 484
-author:
-type: other