Add version constraint to importlib_resources

[sevein]

Based on this recent change in the docs I opted to require importlib_resources>=1.4.0, but tests also passed in jsonschema when using importlib_resources v1.1.0.

Let me know if you want to use importlib_resources>=1.1.0 instead.

For reference: https://importlib-resources.readthedocs.io/en/latest/history.html.

Fixes #876.

[codecov]

Codecov Report

Merging #877 (f8d18fa) into main (3d2eec2) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #877   +/-   ##
=======================================
  Coverage   98.33%   98.33%           
=======================================
  Files          19       19           
  Lines        3125     3125           
  Branches      378      378           
=======================================
  Hits         3073     3073           
  Misses         41       41           
  Partials       11       11           

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[Julian]

Thanks.