Fixes

Author: snapshotpl

composer.json

@@ -9,7 +9,7 @@
         "psr-7",
         "maintenance",
         "psr-15",
-        "psr-11"
+        "psr-17"
     ],
     "require": {
         "php": ">=7.1",

src/MaintenanceMiddleware.php

@@ -2,6 +2,7 @@
 
 namespace PhpMiddleware\Maintenance;
 
+use DateTime;
 use DateTimeInterface;
 use Psr\Http\Message\ResponseFactoryInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -51,7 +52,7 @@ public static function createWithRetryAsSecondsAndRefresh(int $seconds, Response
     public static function createWithRetryAsDateTime(DateTimeInterface $datetime, ResponseFactoryInterface $responseFactory): self
     {
         $instance = new self($responseFactory);
-        $instance->retryAfter = $datetime->format(DateTimeInterface::RFC2822);
+        $instance->retryAfter = $datetime->format(DateTime::RFC2822);
 
         return $instance;
     }