[PHP-FPM] Update to PHP 7.4

docker-compose.yml

@@ -102,7 +102,7 @@ services:
             - rspamd
 
     php-fpm-mailcow:
-      image: mailcow/phpfpm:1.60
+      image: mailcow/phpfpm:1.61
       command: "php-fpm -d date.timezone=${TZ} -d expose_php=0"
       depends_on:
         - redis-mailcow