Update constants.py to fix caching typo

[alanbuxey]

trafficstars

updated the config parameter of no_cashing to no_caching

this may be a breaking change to some configs that have used this value

All Submissions:

• [ x ] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• [ x ] Have you added an explanation of what problem you are trying to solve with this PR?
• [ x ] Have you added information on what your changes do and why you chose this as your solution?
• [ - ] Have you written new tests for your changes?
• [ x ] Does your submission pass tests?
• [ x ] This project follows PEP8 style guide. Have you run your code against the 'flake8' linter?