Update .travis.yml

Author: sujitmandal

.travis.yml

@@ -1,14 +1,14 @@
 language: python
 python:
-  -'2.7'
-  -'3.0'
-  -'3.5'
-  -'3.6'
-  -'3.7'
-  -'3.8'
+  - 2.7
+  - 3.0
+  - 3.5
+  - 3.6
+  - 3.7
+  - 3.8
 
 before_script:
   - composer install --no-interaction
-
+  
 script:
-  - gmail/gmail
+  - vendor/bin/phpunit