Update support builds to use py36

Author: Ryan P Kilby

.travis.yml

@@ -20,8 +20,8 @@ matrix:
       - { python: "3.6", env: DJANGO=master }
       - { python: "3.6", env: DJANGO=1.11 }
       - { python: "3.6", env: DJANGO=2.0 }
-      - { python: "2.7", env: TOXENV=lint }
-      - { python: "2.7", env: TOXENV=docs }
+      - { python: "3.6", env: TOXENV=lint }
+      - { python: "3.6", env: TOXENV=docs }
 
       - python: "3.6"
         env: TOXENV=dist
@@ -30,7 +30,7 @@ matrix:
           - tox
           - tox --installpkg ./dist/djangorestframework-*.whl
 
-      - python: "2.7"
+      - python: "3.6"
         env: TOXENV=readme
         addons:
           apt_packages: pandoc

tox.ini

@@ -38,14 +38,12 @@ deps =
         -rrequirements/requirements-optionals.txt
 
 [testenv:lint]
-basepython = python2.7
 commands = ./runtests.py --lintonly
 deps =
         -rrequirements/requirements-codestyle.txt
         -rrequirements/requirements-testing.txt
 
 [testenv:docs]
-basepython = python2.7
 commands = mkdocs build
 deps =
        -rrequirements/requirements-testing.txt