Use xenial on travis-ci for Python37

.travis.yml

@@ -1,10 +1,8 @@
 language: python
-sudo: false
 python:
   - "3.4"
   - "3.5"
   - "3.6"
-  - "3.7-dev"
 cache:
   pip: true
   directories:
@@ -28,6 +26,15 @@ env:
   - DJANGO="2.1"
   - DJANGO="master"
 matrix:
+  include:
+    - python: "3.7"
+      sudo: required
+      dist: xenial
+      env: DJANGO="2.0"
+    - python: "3.7"
+      sudo: required
+      dist: xenial
+      env: DJANGO="master"
   allow_failures:
     - python: "3.5"
       env: DJANGO="2.1"
@@ -37,15 +44,15 @@ matrix:
       env: DJANGO="2.1"
     - python: "3.6"
       env: DJANGO="master"
-    - python: "3.7-dev"
+    - python: "3.7"
       env: DJANGO="master"
+      sudo: required
+      dist: xenial
   exclude:
     - python: "3.4"
       env: DJANGO="2.1"
     - python: "3.4"
       env: DJANGO="master"
-    - python: "3.7-dev"
-      env: DJANGO="1.11"
 after_success:
   - codecov
 services:

requirements.txt

@@ -92,7 +92,7 @@ pytest==3.4.0
 python-dateutil==2.6.1    # via botocore, elasticsearch-dsl, faker, freezegun
 python3-openid==3.1.0     # via social-auth-core
 pytz==2018.3              # via babel, celery, django
-pyyaml==4.1               # via vcrpy
+pyyaml==4.2b4             # via vcrpy
 raven==6.9.0
 redis==2.10.6             # via celery, django-redis
 requests-oauthlib==0.8.0  # via social-auth-core

tox.ini

@@ -20,7 +20,7 @@ python =
     3.4: py34
     3.5: py35
     3.6: py36
-    3.7-dev: py37
+    3.7: py37
 unignore_outcomes = True
 
 [travis:env]