[Fix] resource name inference for "Serializer"

The previous implementation only supports the class whose name
ends with "Resource".
Alba supports "Serializer" class as well.
This implementation is kind of naive but it works anyway.

lib/alba.rb

@@ -114,7 +114,11 @@ def infer_resource_class(name, nesting: nil)
       raise Alba::Error, 'Inference is disabled so Alba cannot infer resource name. Set inflector before use.' unless Alba.inflector
 
       const_parent = nesting.nil? ? Object : Object.const_get(nesting)
-      const_parent.const_get("#{inflector.classify(name)}Resource")
+      begin
+        const_parent.const_get("#{inflector.classify(name)}Resource")
+      rescue # Retry for serializer
+        const_parent.const_get("#{inflector.classify(name)}Serializer")
+      end
     end
 
     # Configure Alba to symbolize keys