update changelog with 5.1.2 fixes (sourcegraph#54537)

Co-authored-by: Varun Gandhi <varun.gandhi@sourcegraph.com>

CHANGELOG.md

@@ -25,12 +25,20 @@ All notable changes to Sourcegraph are documented in this file.
 
 ### Fixed
 
-- Fixed validation of Bitbucket Cloud configuration in site-admin create/update form. [#54494](https://github.com/sourcegraph/sourcegraph/pull/54494)
+-
 
 ### Removed
 
 -
 
+## 5.1.2
+
+### Fixed
+
+- Fixes a crash when uploading indexes with malformed source ranges (this was a bug in scip-go). [#54304](https://github.com/sourcegraph/sourcegraph/pull/54304)
+- Fixed validation of Bitbucket Cloud configuration in site-admin create/update form. [#54494](https://github.com/sourcegraph/sourcegraph/pull/54494)
+- Fixed race condition with grpc `server.send` message. [#54500](https://github.com/sourcegraph/sourcegraph/pull/54500)
+
 ## 5.1.1
 
 ### Fixed