Update Golang from 1.20.7 to 1.20.8

Changelog: changed

Author: Clemens Beck

.gitlab-ci.yml

@@ -42,7 +42,7 @@ variables:
   # To be used for images that exist only on dev.gitlab.org
   DEV_BUILDER_IMAGE_REGISTRY: 'dev.gitlab.org:5005/cookbooks/gitlab-omnibus-builder'
   PUBLIC_BUILDER_IMAGE_REGISTRY: "registry.gitlab.com/gitlab-org/gitlab-omnibus-builder"
-  BUILDER_IMAGE_REVISION: "4.26.0"
+  BUILDER_IMAGE_REVISION: "4.28.0"
   # The registry to pull the assets image from
   ASSET_REGISTRY: "${CI_REGISTRY}"
   ASSET_SYNC_EXISTING_REMOTE_FILES: "keep"