Update CHANGELOG for 8.39.0

[ci skip]

CHANGELOG

 # Changelog for gitlab-workhorse
 
+## v8.39.0
+
+### Fixed
+- Fix HTTP Range Requests not working on some S3 providers
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/549
+
+### Other
+- Vendor httprs module
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/550
+
+### Performance
+- Cache references in file
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/544
+
 ## v8.38.0
 
 ### Added

changelogs/unreleased/225619-cache-references-v2.yml

----
-title: Cache references in file
-merge_request: 544
-author:
-type: performance

changelogs/unreleased/sh-fix-artifacts-http-range-requests.yml

----
-title: Fix HTTP Range Requests not working on some S3 providers
-merge_request: 549
-author:
-type: fixed

changelogs/unreleased/sh-vendor-httprs.yml

----
-title: Vendor httprs module
-merge_request: 550
-author:
-type: other