rusoto_credential profile.rs aws_session_token parsing problem

[klatu201]

The aws_session_token is a base64 string and can have equal signs at the end as padding, but the basic split code [ https://github.com/rusoto/rusoto/blob/master/rusoto/credential/src/profile.rs - Line 388

 let v: Vec<&str> = unwrapped_line.split('=').collect();
            if !v.is_empty() {
                token = Some(v[1].trim_matches(' ').to_string());
            }

does not correctly pull the full token.

The same issue was fixed in the aws-sdk-cpp back in 2018 - https://github.com/aws/aws-sdk-cpp/pull/766/files