[2.0.0-alpha.4] - 2020-05-21

Changed

• Bump minimum supported Rust version to 1.40
• content_length function is removed, and you can set Content-Length by calling no_chunking function #1439
• BodySize::Sized64 variant has been removed. BodySize::Sized now receives a
  u64 instead of a usize.
• Update base64 dependency to 0.12

Fixed

• Support parsing of SameSite=None #1503