fix: Add filterwarnings ignore for jsonschema.RefResolver DeprecationWarning (#2246)

* Add an ignore to filterwarnings to avoid jsonschema.RefResolver DeprecationWarning

> DeprecationWarning: jsonschema.RefResolver is deprecated as of v4.18.0, in favor
> of the https://github.com/python-jsonschema/referencing library, which provides
> more compliant referencing behavior as well as more flexible APIs for customization.
> A future release will remove RefResolver. Please file a feature request
> (on referencing) if you are missing an API for the kind of customization you need.

  This filterwarning should be removed once pyhf updates to referencing.
  - c.f. #2139

Author: matthewfeickert

pyproject.toml

@@ -214,6 +214,7 @@ filterwarnings = [
     'ignore:`np.bool8` is a deprecated alias for `np.bool_`:DeprecationWarning',  # numpy via tensorflow
     "ignore:module 'sre_constants' is deprecated:DeprecationWarning",  # tensorflow v2.12.0+ for Python 3.11+
     "ignore:ml_dtypes.float8_e4m3b11 is deprecated.",  #FIXME: Can remove when jaxlib>=0.4.12
+    "ignore:jsonschema.RefResolver is deprecated as of v4.18.0, in favor of the:DeprecationWarning",  # Issue #2139
 ]
 
 [tool.coverage.run]