v2.9.0

Features:

• Stabilize support for protocol upgrades on Response #291
• Adds BasicAuth::from_credentials #284
• Adds other::Expect header #266
• Provides a uniform interface for retrieving an optional backtrace from http_types::Error whether or not backtraces are available #258
• Adds a proxy-connection header const #283
• Adds Error::into_inner to retrieve an anyhow Error from a http_types::Error #259

Internal:

• Body Read implementation now will not read beyond the content-length, if one is provided. Previously this logic existed in async-h1, but now is the responsibility of Body #282