chore: adding some missed return types (#209)

Author: hisorange

src/Contracts/ResultInterface.php

@@ -257,5 +257,5 @@ public function deviceModel(): string;
      *
      * @return array
      */
-    public function toArray();
+    public function toArray(): array;
 }

src/Result.php

@@ -459,7 +459,7 @@ public function jsonSerialize(): array
     /**
      * @inheritdoc
      */
-    public function toArray()
+    public function toArray(): array
     {
         return get_object_vars($this);
     }

src/Stages/DeviceDetector.php

@@ -91,7 +91,7 @@ public function __invoke(PayloadInterface $payload): PayloadInterface
      * @param  string $prefix
      * @return array
      */
-    protected function parseVersion(string $version, string $prefix)
+    protected function parseVersion(string $version, string $prefix): array
     {
         $response = [];