Fix ruby warning: * interpreted as argument prefix

I see this warning on MRI 3.3:

```console
ruby/3.3.7/lib/ruby/gems/3.3.0/gems/ruby-openai-6.3.1/lib/openai/client.rb:14: warning: `*' interpreted as argument prefix
```

Using explicit parenthesis fixes the issue

Author: viralpraxis

lib/openai/client.rb

@@ -5,7 +5,7 @@ class Client
     SENSITIVE_ATTRIBUTES = %i[@access_token @admin_token @organization_id @extra_headers].freeze
     CONFIG_KEYS = %i[access_token admin_token api_type api_version extra_headers
                      log_errors organization_id request_timeout uri_base].freeze
-    attr_reader *CONFIG_KEYS, :faraday_middleware
+    attr_reader(*CONFIG_KEYS, :faraday_middleware)
     attr_writer :access_token
 
     def initialize(config = {}, &faraday_middleware)