Allow ApnMessage::interruptionLevel to receive either string or enum

src/ApnMessage.php

@@ -210,9 +210,11 @@ public function sound(null|string|Sound $sound = 'default'): self
     /**
      * Set the interruptionLevel of the notification.
      */
-    public function interruptionLevel(?string $interruptionLevel = 'active'): self
+    public function interruptionLevel(string|ApnMessageInterruptionLevel|null $interruptionLevel = 'active'): self
     {
-        $this->interruptionLevel = $interruptionLevel;
+        $this->interruptionLevel = $interruptionLevel instanceof ApnMessageInterruptionLevel
+            ? $interruptionLevel->value
+            : $interruptionLevel;
 
         return $this;
     }

tests/ApnMessageTest.php

@@ -5,6 +5,7 @@
 use DateTime;
 use Mockery;
 use NotificationChannels\Apn\ApnMessage;
+use NotificationChannels\Apn\ApnMessageInterruptionLevel;
 use Pushok\Client;
 
 class ApnMessageTest extends TestCase
@@ -78,7 +79,7 @@ public function it_can_set_sound()
     }
 
     /** @test */
-    public function it_can_set_interruption_level()
+    public function it_can_set_interruption_level_as_string()
     {
         $message = new ApnMessage;
 
@@ -88,6 +89,17 @@ public function it_can_set_interruption_level()
         $this->assertEquals($message, $result);
     }
 
+    /** @test */
+    public function it_can_set_interruption_level_as_enum()
+    {
+        $message = new ApnMessage;
+
+        $result = $message->interruptionLevel(ApnMessageInterruptionLevel::Critical);
+
+        $this->assertEquals('critical', $message->interruptionLevel);
+        $this->assertEquals($message, $result);
+    }
+
     /** @test */
     public function it_can_set_sound_to_default()
     {