CHANGELOG.md: update

Author: razzmatazz

CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
-* Upgrade Roslyn to 4.11.0
+* Upgrade Roslyn to 4.12.0
 * Fix an issue where server breaks when inspecting class/properties involved in source-generated code:
   - By @granitrocky in https://github.com/razzmatazz/csharp-language-server/pull/189
 * Make sure textDocument/findReferences respects Context.IncludeDeclaration