Stop relying on unmaintained p7zip

Currently, the tests of the 7z functionality in this project fail when run against the system-provided 7z command from the 7zip upstream. They seem to only work when run against p7zip, which is dead upstream and has thus been removed from Fedora in favor of 7zip. https://pypi.org/project/extractcode-7z/ also seems to contain a very old pre-built p7zip binary. Can you please consider switching out p7zip for 7zip in extractcode upstream and in the pre-built extractcode-7z on PyPI as well? It is unclear to me whether these failures are issues with the tests or are issues with the actual code.

There is more context about this issue and the history of the p7zip and 7zip projects in https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/VAI3BSN24Z2BSOPNLYKPR5FGZHUKIABZ/.

### Test failures

```
# FAILED tests/test_archive.py::TestGetExtractorTest::test_windows_media_player_skins_are_zip
# FAILED tests/test_archive.py::TestZip::test_get_best_handler_nuget_is_selected_over_zip
# FAILED tests/test_archive.py::TestZip::test_get_best_handler_nuget_is_selected_over_zip2
# FAILED tests/test_archive.py::TestZip::test_get_best_handler_nuget_is_selected_over_zip3
# FAILED tests/test_archive.py::TestZip::test_list_zip_with_relative_path_deeply_nested_with_7zip
# FAILED tests/test_archive.py::TestTar::test_extract_python_testtar_tar_archive_with_special_files
# FAILED tests/test_archive.py::TestCpio::test_extract_cpio_broken_7z - Asserti...
# FAILED tests/test_archive.py::TestExtractArchiveWithIllegalFilenamesWithSevenzipOnPosix::test_extract_7zip_with_weird_filenames_with_sevenzip_posix
# FAILED tests/test_archive.py::TestExtractArchiveWithIllegalFilenamesWithSevenzipOnPosix::test_extract_ar_with_weird_filenames_with_sevenzip_posix
# FAILED tests/test_archive.py::TestExtractArchiveWithIllegalFilenamesWithSevenzipOnPosix::test_extract_cpio_with_weird_filenames_with_sevenzip_posix
# FAILED tests/test_archive.py::TestExtractArchiveWithIllegalFilenamesWithSevenzipOnPosix::test_extract_tar_with_weird_filenames_with_sevenzip_posix
# FAILED tests/test_archive.py::TestExtractArchiveWithIllegalFilenamesWithSevenzipOnPosix::test_extract_zip_with_weird_filenames_with_sevenzip_posix
# FAILED tests/test_sevenzip.py::TestSevenZipListEntries::test_list_entries_of_special_tar
# FAILED tests/test_sevenzip.py::TestSevenZipListEntries::test_list_entries_with_weird_names_7z
# FAILED tests/test_sevenzip.py::TestSevenZipFileByFile::test_extract_file_by_file_weird_names_ar
# FAILED tests/test_sevenzip.py::TestSevenZipFileByFile::test_extract_file_by_file_weird_names_cpio
# FAILED tests/test_sevenzip.py::TestSevenZipFileByFile::test_extract_file_by_file_weird_names_tar
# FAILED tests/test_sevenzip.py::TestSevenZipFileByFile::test_extract_file_by_file_weird_names_zip
# FAILED tests/test_sevenzip.py::TestSevenZipFileByFile::test_extract_file_by_file_with_weird_names_7z
```