Remove dead ext-mcrypt dependency

mcrypt was removed in PHP 7.2 and is not referenced anywhere in the
codebase. Also regenerated composer.lock.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: carlbennett

composer.json

@@ -41,7 +41,6 @@
         "ext-http": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "ext-mcrypt": "*",
         "ext-pdo": "*",
         "geoip2/geoip2": "~2.0",
         "php-64bit": "^8.3",