Add Python3.10 to Tox and CI environments

Author: eht16

.github/workflows/tests.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python: ['3.6', '3.7', '3.8', '3.9']
+        python: ['3.6', '3.7', '3.8', '3.9', '3.10']
       fail-fast: false
 
     steps:

tox.ini

@@ -6,7 +6,7 @@
 [tox]
 skip_missing_interpreters = true
 envlist =
-    docs,py36,py37,py38,py39,pypy3
+    docs,py36,py37,py38,py39,py310,pypy3
 
 logstash_async_modules = logstash_async tests