Add php-bcmath to default production PHP

The campus readership map is planned for an update soon, and will depend
on php-bcmath to support Google Analytics 4. This follows the addition
in development. At present, this materializes as php8.1-bcmath.

manifests/profile/www_lib/php.pp

@@ -49,6 +49,7 @@
       "php${default_php_version}-msgpack",
       "php${default_php_version}-redis",
       "php${default_php_version}-xdebug",
+      "php${default_php_version}-bcmath",
       "php${default_php_version}-curl",
       "php${default_php_version}-gd",
       "php${default_php_version}-ldap",