Fix typo in config_description hash key

Typo “seriserialization_options” → “serialization_options”. I couldn't find any references to this misspelt key in the current codebase, neither any GitHub search result besides forks of jsonapi-resources 😄 So I presume it's safe to correct it.

The only usage of the affected `config_description` method I found ends up using the keys as [part of a cache key](https://github.com/cerebris/jsonapi-resources/blob/d87cd2d2e80ab7660081c32db2303f196860b060/lib/jsonapi/resource_set.rb#L28), which won't be affected either.

Author: tobias-bischoff

lib/jsonapi/resource_serializer.rb

@@ -131,7 +131,7 @@ def config_key(resource_klass)
     def config_description(resource_klass)
       {
         class_name: self.class.name,
-        seriserialization_options: serialization_options.sort.map(&:as_json),
+        serialization_options: serialization_options.sort.map(&:as_json),
         supplying_attribute_fields: supplying_attribute_fields(resource_klass).sort,
         supplying_relationship_fields: supplying_relationship_fields(resource_klass).sort,
         link_builder_base_url: link_builder.base_url,