Add phpstan level 7(#544)

app/StorageProviders/StorageProvider.php

@@ -7,8 +7,15 @@
 
 interface StorageProvider
 {
+    /**
+     * @return array<string, string>
+     */
     public function validationRules(): array;
 
+    /**
+     * @param  array<string, mixed>  $input
+     * @return array<string, mixed>
+     */
     public function credentialData(array $input): array;
 
     public function connect(): bool;