Update CHANGELOG for 8.51.0

[ci skip]

CHANGELOG

 # Changelog for gitlab-workhorse
 
+## v8.51.0
+
+### Changed
+- Allow configure image resizing params
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/615
+
+### Fixed
+- Fix processing lsif dump with repeating lines with inVs
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/621
+  Contributed by Pavel Kuznetsov
+
+### Other
+- Add CODEOWNERS with listed maintainers
+  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/623
+
 ## v8.50.0
 
 ### Added

changelogs/unreleased/298-set-img-resizing-const-via-env-vars.yml

----
-title: Allow configure image resizing params
-merge_request: 615
-author:
-type: changed

changelogs/unreleased/305-lsif-arrays.yml

----
-title: Fix processing lsif dump with repeating lines with inVs
-merge_request: 621
-author: Pavel Kuznetsov
-type: fixed

changelogs/unreleased/id-add-codeowners-file.yml

----
-title: Add CODEOWNERS with listed maintainers
-merge_request: 623
-author:
-type: other