Fix deprecated pytest mark

mark.optionalhook has been deprecated (https://docs.pytest.org/en/latest/deprecations.html#configuring-hook-specs-impls-using-markers)

Author: jakevdp

reporting.py

@@ -10,7 +10,7 @@
 
 from hypothesis.strategies import SearchStrategy
 
-from pytest import mark, fixture
+from pytest import hookimpl, fixture
 try:
     import pytest_jsonreport # noqa
 except ImportError:
@@ -44,7 +44,7 @@ def to_json_serializable(o):
 
     return o
 
-@mark.optionalhook
+@hookimpl(optionalhook=True)
 def pytest_metadata(metadata):
     """
     Additional global metadata for --json-report.
@@ -91,7 +91,7 @@ def finalizer():
 
     request.addfinalizer(finalizer)
 
-@mark.optionalhook
+@hookimpl(optionalhook=True)
 def pytest_json_modifyreport(json_report):
     # Deduplicate warnings. These duplicate warnings can cause the file size
     # to become huge. For instance, a warning from np.bool which is emitted