Fixing the 'Bad Interpreter' Error from AWS and Python 3.7

This is mostly a note to myself, but it might help others out there.

If you're using awscli on your computer for something, you may suddenly start seeing an error like this crop up in your terminal:

.zshrc: /usr/local/bin/aws: bad interpreter: /usr/local/opt/python/bin/python3.6: no such file or directory

This is because you've probably installed awscli in the past, but more recently upgraded your system Python to version 3.7, not 3.6 (which old versions of awscli worked with).

The fix is easy, and in two parts. First, install the latest awscli:

brew reinstall awscli

Second, to make sure brew knows which version to use:

brew link --overwrite awscli

This should clear up that error.