Remove unreleased feature from changelog

extensions/ql-vscode/CHANGELOG.md

@@ -2,9 +2,7 @@
 
 ## [Unreleased]
 
-- Add the AST Viewer to inspect the QL AST of a source file in a database. Currently, only available for C/C++ sources.
 - Fix error with choosing qlpack search path.
-- Add the AST Viewer to inspect the QL AST of a source file in a database. Currently, only available for C/C++ sources.
 - Fix pagination when there are no results.
 - Suppress database downloaded from URL message when action canceled.
 - Fix QL test discovery to avoid showing duplicate tests in the test explorer.