Add a deployment stage. Ref #66.

.travis.yml

@@ -4,15 +4,30 @@ sudo: false # Use container-based infrastructure
 matrix:
   fast_finish: true
   include:
-    - python: 3.7
-      dist: xenial
-      sudo: true
-    - python: 3.6
-    - python: 3.5
-    - python: 3.4
-    - python: pypy3
-    - python: 2.7
-    - python: pypy
+  - python: 3.7
+    dist: xenial
+    sudo: true
+  - python: &latest_py3 3.6
+  - python: 3.5
+  - python: 3.4
+  - python: pypy3
+  - python: 2.7
+  - python: pypy
+  - stage: deploy
+    if: tag IS present
+    python: *latest_py3
+    install: skip
+    script: skip
+    deploy:
+      provider: pypi
+      on:
+        tags: true
+        all_branches: true
+      user: jaraco
+      password:
+        secure: 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
+      distributions: dists
+      skip_cleanup: true
 
 install:
  - pip install coverage tox-travis