Add Python 3.10 and drop Python 3.5 from CI (#486)

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py35,py36,py37,py38,py39,py39-dev,pypy,pypy3,coverage-report
+envlist = py27,py36,py37,py38,py39,py310,py311-dev,pypy,pypy3,coverage-report
 
 
 [testenv]
@@ -25,16 +25,6 @@ commands =
     coverage run --parallel -m pytest {posargs}
     flake8 . --count --show-source --statistics
 
-[testenv:py35]
-deps=
-   dbus-python
-   -r{toxinidir}/requirements.txt
-   -r{toxinidir}/dev-requirements.txt
-commands =
-    python setup.py compile_catalog
-    coverage run --parallel -m pytest {posargs}
-    flake8 . --count --show-source --statistics
-
 [testenv:py36]
 deps=
    dbus-python
@@ -75,7 +65,17 @@ commands =
     coverage run --parallel -m pytest {posargs}
     flake8 . --count --show-source --statistics
 
-[testenv:py39-dev]
+[testenv:py310]
+deps=
+   dbus-python
+   -r{toxinidir}/requirements.txt
+   -r{toxinidir}/dev-requirements.txt
+commands =
+    python setup.py compile_catalog
+    coverage run --parallel -m pytest {posargs}
+    flake8 . --count --show-source --statistics
+
+[testenv:py311-dev]
 deps=
    dbus-python
    -r{toxinidir}/requirements.txt