Remove missing version from changelog.

It failed to deploy. 15.0.2 only exists as a tag at this point.

Author: HexDecimal

CHANGELOG.md

@@ -6,8 +6,6 @@ This project adheres to [Semantic Versioning](https://semver.org/) since version
 ## [Unreleased]
 
 ## [15.0.3] - 2023-05-25
-
-## [15.0.2] - 2023-05-25
 ### Deprecated
 - Deprecated all libtcod color constants.  Replace these with your own manually defined colors.
   Using a color will tell you the color values of the deprecated color in the warning.