BUG: Attempt to fix schema download using jsdelivr instead of GitHub raw

[jcfr]

See https://www.jsdelivr.com/?docs=gh and https://rawgit.com/

Attempt to fix error like the following:

Error: schemafile could not be parsed as JSON
SchemaParseError: https://raw.githubusercontent.com/Slicer/Slicer/main/Schemas/slicer-extension-catalog-entry-schema-v1.0.0.json
  in "/home/runner/.cache/pre-commit/repof4twk6ja/py_env-python3.9/lib/python3.9/site-packages/check_jsonschema/checker.py", line 53
  >>> return self._schema_loader.get_validator(

  caused by

  FailedFileLoadError: Failed to parse https://raw.githubusercontent.com/Slicer/Slicer/main/Schemas/slicer-extension-catalog-entry-schema-v1.0.0.json
    in "/home/runner/.cache/pre-commit/repof4twk6ja/py_env-python3.9/lib/python3.9/site-packages/check_jsonschema/schema_loader/readers.py", line 27
    >>> schema = callback()

    caused by

    JSONDecodeError: Expecting value: line 1 column 1 (char 0)
      in "/home/runner/.cache/pre-commit/repof4twk6ja/py_env-python3.9/lib/python3.9/site-packages/check_jsonschema/parsers/__init__.py", line 92
      >>> return loadfunc(data)

      caused by

      StopIteration: 0
        in "/opt/hostedtoolcache/Python/3.9.19/x64/lib/python3.9/json/decoder.py", line 353
        >>> obj, end = self.scan_once(s, idx)

Source: https://github.com/Slicer/ExtensionsIndex/actions/runs/9520665504/job/26246426798?pr=2055

[lassoan]

Nice! I've never heard of www.jsdelivr.com but seems useful.