Fix PyparsingDeprecationWarning with pyparsing 3.3.

[sebastic]

As reported in Debian Bug #1129563:

pyparsing 3.3.2-1 is now in experimental.

The autopkgtest for fiona are failing:

https://qa.debian.org/excuses.php?experimental=1&package=pyparsing

132s ___________________ ERROR collecting tests/test_features.py ____________________
132s tests/test_features.py:10: in <module>
132s     from fiona.features import (  # type: ignore
132s /usr/lib/python3/dist-packages/fiona/features.py:15: in <module>
132s     from ._vendor import snuggs
132s /usr/lib/python3/dist-packages/fiona/_vendor/snuggs.py:161: in <module>
132s     op = oneOf(" ".join(op_map.keys())).set_parse_action(
132s          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
132s /usr/lib/python3/dist-packages/pyparsing/util.py:472: in _inner
132s     warnings.warn(
132s E   pyparsing.warnings.PyparsingDeprecationWarning: 'oneOf' deprecated - use 'one_of'
132s =============================== warnings summary ===============================

Please consider applying this trivial patch hereunder.

pyparsing is itself a requirement of the new OpenStack release.

https://wiki.debian.org/OpenStack/gazpacho-to-update