Does not build on ARM64. Requires dependency update.

This project does not currently build on ARM64 due to https://github.com/awslabs/aws-crt-python/issues/228
This has already been fixed in awscrt which is a dependency of awsiotsdk.
Updating to the latest version of awsiotsdk in requirements.txt will resolve this build problem on arm64.
Updating awscrt seems to cause a small change in behaviour. Only the root CA cert must be provided in DER instead of PEM format or else the TLS context can't be set up.
If you run into any other problems then `io.init_logging(awscrt.io.LogLevel.Trace, 'stdout')` is your friend.

Start with requirements.txt and the ARM64 build path described in the issue; verify the current awsiotsdk and awscrt versions and reproduce the build failure if possible. Check the TLS setup using the root CA in DER format and use io.init_logging(awscrt.io.LogLevel.Trace, 'stdout') for diagnostics; done means ARM64 builds successfully and TLS setup works with the updated dependency.

Written by the indexing model from the issue text.