Mention PHP version requirement change in changelog

Author: SomeMWDev

README.md

@@ -105,6 +105,7 @@ The Font Awesome Free package is included in the extension. See its
 
 Released on July 22, 2025.
 
+* Raised the minimum PHP version from 7.4.3 to 8.1.0
 * Raised the minimum MediaWiki version from 1.39 to 1.43
 
 ### Version 3.0.0