Asynchronous HTTP Request and Promise

Changes for v0.2.4 - 2023-08-15T15:35:14Z

• Added method as_form_data in module HTTP:😛romise::Message
• Added method url_encode to HTTP:😛romise::Request
• Correcting a typo in HTTP:😛romise::Stream::Base64
• Improved documentation in HTTP:😛romise:😛ool