Reformatted .travis.yml

Author: domdfcoding

.travis.yml

@@ -1,15 +1,15 @@
 language: python
 dist: xenial
 python:
-- '3.6'
-- '3.7'
-- "3.8"
+  - '3.6'
+  - '3.7'
+  - "3.8"
 install:
-- pip install coveralls -r tests/requirements.txt
+  - pip install coveralls -r tests/requirements.txt
 script:
-- pytest --cov=domdf_python_tools tests/
+  - pytest --cov=domdf_python_tools tests/
 after_success:
-- coveralls
+  - coveralls
 deploy:
   provider: pypi
   user: "DomDF"