add support and testing for python 3.10

.github/workflows/ci.yml

@@ -66,6 +66,9 @@ jobs:
             - os: ubuntu-20.04
               python-version: 3.9
               toxenv: py39
+            - os: ubuntu-20.04
+              python-version: 3.10
+              toxenv: py310
             - os: macos-latest
               # note: it seems that 3.8 and 3.9 are currently broken,
               # neverending RuntimeError crashes...

setup.py

@@ -875,6 +875,7 @@ 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',
     ],

tox.ini

@@ -2,7 +2,7 @@
 # fakeroot -u tox --recreate
 
 [tox]
-envlist = py{35,36,37,38,39}
+envlist = py{35,36,37,38,39,310}
 
 [testenv]
 deps =