testing/py3-zimscraperlib: disable on loongarch64

Tests fail, and it takes 27 minutes to find this out

=========================== short test summary info ============================
FAILED tests/download/test_download.py::test_youtube_download_serial[https://vimeo.com/619427082-619427082_0]
FAILED tests/download/test_download.py::test_youtube_download_serial[https://vimeo.com/619427082-619427082_1]
FAILED tests/download/test_download.py::test_youtube_download_nowait - assert...
FAILED tests/download/test_download.py::test_youtube_download_contextmanager
FAILED tests/zim/test_archive.py::test_search - RuntimeError: Cluster pointer...
FAILED tests/zim/test_archive.py::test_get_tags - RuntimeError: Cluster point...
FAILED tests/zim/test_zim_creator.py::test_urlitem_html - subprocess.CalledPr...
FAILED tests/zim/test_zim_creator.py::test_urlitem_binary - subprocess.Called...
FAILED tests/zim/test_zim_creator.py::test_filelikeprovider_nosize - requests...
FAILED tests/zim/test_zim_creator.py::test_urlprovider - subprocess.CalledPro...
FAILED tests/zim/test_zim_creator.py::test_urlprovider_nolength - subprocess....
==== 11 failed, 318 passed, 4 deselected, 32 warnings in 1672.21s (0:27:52) ====