Fix travis file due to flask dependency change

.travis.yml

@@ -7,23 +7,17 @@ python:
   - '3.4'
   - '3.5'
   - '3.6'
+  - '3.7'
+  - '3.8'
   - pypy
-
-# from https://github.com/travis-ci/travis-ci/issues/9815
-# https://github.com/travis-ci/travis-ci/issues/9069#issuecomment-425720905
-# Enable 3.7 without globally enabling sudo and dist: xenial for other build jobs
-matrix:
-  include:
-    - python: 3.7
-      dist: xenial
-      sudo: true
 
 env:
-- FLASK=0.10.1
-- FLASK=0.10
-
+- FLASK=0.10.1 WERKZEUG_DEP="werkzeug==0.16.1"
+- FLASK=0.10 WERKZEUG_DEP="werkzeug==0.16.1"
+- FLASK=1.0 WERKZEUG_DEP=""
+- FLASK=1.1 WERKZEUG_DEP=""
 install:
-  - pip install -U setuptools pep8 six coverage docutils pygments flask==$FLASK
+  - pip install -U setuptools pep8 six coverage docutils pygments flask==$FLASK $WERKZEUG_DEP
 
 script:
   - coverage erase

tests/extension/test_app_extension.py

@@ -204,7 +204,7 @@ class AppExtensionString(FlaskCorsTestCase):
     def setUp(self):
         self.app = Flask(__name__)
         CORS(self.app, resources=r'/api/*',
-             headers='Content-Type',
+             allow_headers='Content-Type',
              expose_headers='X-Total-Count',
              origins='http://bar.com')