Fixed some typos in tests

Author: languagetub

tests/IntegrationTest.php

@@ -159,7 +159,7 @@ public function a_request_with_a_config_key_will_use_the_correct_signing_secret(
             ],
         ];
 
-        Arr::set($payload, 'signature', $this->determineMailgunSignature($payload));
+        Arr::set($payload, 'signature', $this->determineMailgunSignature($payload, 'somekey'));
 
         $this
             ->postJson('mailgun-webhooks/somekey', $payload)

tests/TestCase.php

@@ -87,7 +87,7 @@ protected function determineMailgunSignature(array $payload, string $configKey =
         return [
             'timestamp' => $timestamp,
             'token' => $token,
-            'signature' => hash_hmac('sha256', "{$timestamp}.{$token}", $secret),
+            'signature' => hash_hmac('sha256', "{$timestamp}{$token}", $secret),
         ];
     }
 }