Update src/PushTemplate.php

src/PushApi.php

@@ -106,7 +106,7 @@ class PushApi
             }
         }
 
-        return $client->request('post', $url, [
+        return $client->request('POST', $url, [
             'multipart' => $multipart_form,
             'headers' => [
                 'Authorization' => 'Bearer ' . $this->api_key,

src/PushTemplate.php

@@ -297,7 +297,7 @@ class PushTemplate implements \JsonSerializable
         ];
     }
 
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return $this->toArray();
     }