remove py310 support declaration again, see #5729

setup.py

@@ -875,7 +875,6 @@ setup(
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
-        'Programming Language :: Python :: 3.10',
         'Topic :: Security :: Cryptography',
         'Topic :: System :: Archiving :: Backup',
     ],