vici: Remove support for Python 2

Python 2 is dead and unmaintained for a while now. Time to stop carrying
on its support.

src/libcharon/plugins/vici/python/tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, py36, py37, py38, py39
+envlist = py36, py37, py38, py39
 
 [testenv]
 deps =
@@ -7,10 +7,6 @@ deps =
 	pytest-pycodestyle
 commands = pytest --pycodestyle
 
-[testenv:py{27}]
-deps = pytest
-commands = pytest
-
 [pycodestyle]
 max-line-length = 80
 show-source = True