Add newlines and strict types check.

app/Helpers/Webhook/Sha3SignatureGenerator.php

@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /*
  * Sha3SignatureGenerator.php
  * Copyright (c) 2020 james@firefly-iii.org
@@ -67,4 +68,4 @@ class Sha3SignatureGenerator implements SignatureGeneratorInterface
         // Schemes start with v, followed by an integer. Currently, the only valid live signature scheme is v1.
         return sprintf('t=%s,v%d=%s', $timestamp, $this->getVersion(), $signature);
     }
-}
+}

app/Helpers/Webhook/SignatureGeneratorInterface.php

@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /*
  * SignatureGeneratorInterface.php
  * Copyright (c) 2020 james@firefly-iii.org
@@ -41,4 +42,4 @@ interface SignatureGeneratorInterface
      * @return string
      */
     public function generate(WebhookMessage $message): string;
-}
+}