test_save_as_mofile fails with gettext 0.22+ #150

$ tox -e py311
py311: pip-23.3.2-py3-none-any.whl already present in /home/mgorny/.local/share/virtualenv/wheel/3.11/embed/3/pip.json
py311: wheel-0.42.0-py3-none-any.whl already present in /home/mgorny/.local/share/virtualenv/wheel/3.11/embed/3/wheel.json
py311: setuptools-69.0.3-py3-none-any.whl already present in /home/mgorny/.local/share/virtualenv/wheel/3.11/embed/3/setuptools.json
py311: install_deps> python -I -m pip install coverage
.pkg: install_requires> python -I -m pip install 'setuptools>=40.8.0' wheel
.pkg: _optional_hooks> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: get_requires_for_build_sdist> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: get_requires_for_build_wheel> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: install_requires_for_build_wheel> python -I -m pip install wheel
.pkg: prepare_metadata_for_build_wheel> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: build_sdist> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
py311: install_package> python -I -m pip install --force-reinstall --no-deps /tmp/polib/.tox/.tmp/package/1/polib-1.2.0.tar.gz
py311: commands[0]> coverage run tests/tests.py
.................................................................................F.....
======================================================================
FAIL: test_save_as_mofile (__main__.TestPoFile.test_save_as_mofile)
Test for the POFile.save_as_mofile() method.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/polib/tests/tests.py", line 654, in test_save_as_mofile
    self.assertEqual(s1, s2)
AssertionError: b"\xd[276 chars]0\x001\x01\x00\x00\x06\x01\x00\x00&\x00\x00\x0[789 chars]\x00" != b"\xd[276 chars]0\x00,\x01\x00\x00\x06\x01\x00\x00&\x00\x00\x0[807 chars]\x00"

----------------------------------------------------------------------
Ran 87 tests in 1.078s

FAILED (failures=1)
py311: exit 1 (1.50 seconds) /tmp/polib> coverage run tests/tests.py pid=938030
.pkg: _exit> python /usr/lib/python3.12/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  py311: FAIL code 1 (18.01=setup[16.51]+cmd[1.50] seconds)
  evaluation failed :( (18.16 seconds)