Release 0.20.0 - Githubissues

Remove deprecation warnings due to usage of utcnow and utcfromtimestamp. Thanks to Raphael Krupinski.
httpx_auth.AWS4Auth.default_include_headers value kept growing in size every time a new httpx_auth.AWS4Auth instance was created with security_token parameter provided. Thanks to Miikka Koskinen.
httpx_auth.AWS4Auth is now based almost entirely on AWS documentation, diverging from the original implementation based on requests-aws4auth and solving implementation issues in the process.
- As the AWS documentation might be wrong or not exhaustive enough, feel free to open issues, should you encounter edge cases.

httpx_auth.AWS4Auth.default_include_headers is not available anymore, use httpx_auth.AWS4Auth include_headers parameter instead to include additional headers if the default does not fit your need (refer to documentation for an exhaustive list).
httpx_auth.AWS4Auth include_headers values will not be stripped anymore, meaning that you can now include headers prefixed and/or suffixed with blank spaces.
httpx_auth.AWS4Auth does not includes date header by default anymore. You will have to provide it via include_headers yourself if you need to.
- Note that it should not be required as httpx_auth.AWS4Auth is sending x-amz-date by default and AWS documentation states that the request date can be specified by using either the HTTP Date or the x-amz-date header. If both headers are present, x-amz-date takes precedence.
httpx_auth.AWS4Auth include_headers does not needs to include host, content-type or x-amz-* anymore as those headers will always be included. It is now expected to be provided as a list of additional headers.
httpx_auth.AWS4Auth will not modify the headers values spaces when computing the canonical headers, only trim leading and trailing whitespaces as per AWS documentation.

Colin-b / httpx_auth