Add json schema to core and make jsonschema dependency optional

[alejoe91]

Fixes #321

@musicinmybrain can you test this solution?

I moved the probe.json.schema to the package directory and added it to be included in the wheel.
In addition, the jsonschema package is only imported when calling validate_probe_dict, so it should be safer.

Let me know what you think!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.55%. Comparing base (5e45e90) to head (0d9a3ad).
Report is 57 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #326   +/-   ##
=======================================
  Coverage   89.55%   89.55%           
=======================================
  Files          12       12           
  Lines        1944     1944           
=======================================
  Hits         1741     1741           
  Misses        203      203           

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[samuelgarcia]

This replace #322
Thank ALessio.

[musicinmybrain]

@musicinmybrain can you test this solution?

I tried this out in https://src.fedoraproject.org/rpms/python-probeinterface/pull-request/5. It seems fine to me. Thanks!