Allow PHP 8.6 in phpstan/turbo composer.json

Turbo binaries for PHP 8.6 are already shipped as PIE release assets,
but the php constraint stopped at ~8.5.0, so PIE refused to install
the extension on PHP 8.6.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LSeeJXEA18Ma6X4qyx1xMx

Author: ondrejmirtes

turbo-ext/composer.json

@@ -7,7 +7,7 @@
 	"type": "php-ext",
 	"homepage": "https://phpstan.org",
 	"require": {
-		"php": "~8.3.0 || ~8.4.0 || ~8.5.0"
+		"php": "~8.3.0 || ~8.4.0 || ~8.5.0 || ~8.6.0"
 	},
 	"php-ext": {
 		"extension-name": "phpstan_turbo",