Fix Python3 issues and add type hints to run_sk_stress_test

[ahoppen]

• Open files that should be parsed as JSON as normal (non-binary) files
• Revert [run_sk_stress_test] Replace non-ascii characters when outputting to an ascii tty #345 because it was causing issues. Maybe the underlying issue is fixed in Python3. At least I haven’t been able to reproduce it 🤷
• While doing this, I also added a few type hints to the Python script.

[justice-adams-apple]

My mistake for not catching this. Thank you for the quick PR 👍

Appreciate it!

If you need to reconfigure the stdout encoding in Python3 we can do so with
sys.stdout.reconfigure(encoding='YOUR_ENCODING')

But it should default to utf-8 so I think it's OK to leave out