remove alpine tests for now php/php-src#18779

Author: henderkes

src/globals/test-extensions.php

@@ -24,7 +24,7 @@
     'macos-13',
     // 'macos-14',
     'macos-15',
-    'ubuntu-latest',
+    // 'ubuntu-latest',
     'ubuntu-22.04',
     // 'ubuntu-24.04',
     'ubuntu-22.04-arm',