Pin jsonschema to 3.2.0 (SC-466)

[TheRealFalcon]

Proposed Commit Message

Pin jsonschema to 3.2.0

On unit tests, tox is attempting to install 4.0, which fails two of
the unit tests, and fails python 3.5 as it is not compatible.

Additional Context

Test Steps

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[blackboxsw]

Landing this as it unblocks CI, but the 4.0.1 release (released yesterday) of jsonschema no longer rasises expected schemavalidation errrors. due to 'format': 'hostname' declarations. I think we should sort that inconsistency with a followup PR.