Update CHANGELOG.md 2.0.0 release date

Author: Brendan Hay

lib/amazonka/CHANGELOG.md

@@ -1,7 +1,7 @@
 # Change Log
 
 ## [2.0.0](https://github.com/brendanhay/amazonka/tree/2.0.0)
-Released: **?**, Compare: [2.0.0-rc2](https://github.com/brendanhay/amazonka/compare/2.0.0-rc2...2.0.0)
+Released: **28 July 2023**, Compare: [2.0.0-rc2](https://github.com/brendanhay/amazonka/compare/2.0.0-rc2...2.0.0)
 
 ### Changed