fix travis config

.travis.yml

@@ -1,39 +1,32 @@
-  language: python
-  python:
-    - "3.5"
-    - "3.6"
-    - "3.7-dev"
+language: python
+python:
+  - '3.5'
+  - '3.6'
+  - 3.7-dev
+cache:
+  - pip
+  - apt
+addons:
+  apt:
+    packages: libjs-mathjax
+script:
+  - python -c "import graphtools"
+  - 'pip install -U .[test]'
+  - 'if [ "$TRAVIS_PYTHON_VERSION" != "3.5" ]; then black . --check --diff; fi'
+  - python setup.py test
+  - 'pip install -U .[doc]'
+  - cd doc; make html
+  - cd ..
+deploy:
+  provider: pypi
+  user: scottgigante
+  password: '${PYPI_PASSWORD}'
+  distributions: sdist bdist_wheel
+  skip_existing: true
+  cleanup: false
+  'on':
+    tags: true
+    branch: master
+after_success:
+  - coveralls
 
-  sudo: required
-
-  cache:
-    - pip
-    - apt
-
-  addons:
-    apt:
-      packages:
-        libjs-mathjax
-
-  script:
-    - python -c "import graphtools"
-    - pip install -U .[test]
-    - if [ "$TRAVIS_PYTHON_VERSION" != "3.5" ]; then black . --check --diff; fi
-    - python setup.py test
-    - pip install -U .[doc]
-    - cd doc; make html
-    - cd ..
-
-  deploy:
-    provider: pypi
-    user: scottgigante
-    password: ${PYPI_PASSWORD}
-    distributions: sdist bdist_wheel
-    skip_existing: true
-    skip_cleanup: true
-    on:
-      tags: true
-      branch: master
-
-  after_success:
-    - coveralls