Improve Travis deploy configuration

Author: Cito

.travis.yml

@@ -26,9 +26,12 @@ cache:
     - $HOME/.cache/pre-commit
 deploy:
   provider: pypi
-  user: syrusakbary
+  distributions: "sdist bdist_wheel"
   on:
+    branch: master
     tags: true
+    python: 3.7
+  skip_existing: true
+  user: syrusakbary
   password:
     secure: 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
-  distributions: "sdist bdist_wheel"