remove json from requirements.txt

[Timothy-Pulliam]

$ python --version
Python 3.6.5
$ python -m pip install json
Collecting json
  Could not find a version that satisfies the requirement json (from versions: )

However, taking json out of requirements.txt fixes the issue.

[techcentaur]

Yes, that's right. Because you don't need to install json by pip, it is already included in the standard modules. Thank you.