chore: Fix basepython for mypy-py2. (#143)

Author: lizroth

tox.ini

@@ -189,7 +189,7 @@ commands =
     {[testenv:mypy-coverage]commands}
 
 [testenv:mypy-py2]
-basepython = {[testenv:mypy-common]basepython}
+basepython = python2.7
 deps = {[testenv:mypy-common]deps}
 commands =
     python -m mypy \