Update release date of Wasmtime 6.0.0 (#5836)

Co-authored-by: Wasmtime Publish <[email protected]>

Author: wasmtime-publish

RELEASES.md

@@ -12,7 +12,7 @@ Unreleased.
 
 ## 6.0.0
 
-Unreleased.
+Released 2023-02-20
 
 ### Added