AWS CLI is using Python 2 instead of Python 3
Why is it really an issue?
I assume you installed the AWS CLI tool by downloading the installer directly. If you want to "fix" it then uninstall the CLI tool, and then install it through pip with pip install awscli.
I have installed Python3 and pip3 on my Macbook pro. 
Running python --version shows Python 3.6.3
Running pip --version shows pip 9.0.1 from /usr/local/lib/python3.6/site-packages (python 3.6)
however running aws --version shows aws-cli/1.11.170 Python/2.7.10 Darwin/16.7.0 botocore/1.7.28
Looks like it's using python2. How do I fix this?