ci: seperate build step

.travis.yml

@@ -19,11 +19,26 @@ script:
 - ./tests/test_examples.sh examples/
 after_success:
 - bash <(curl -s https://codecov.io/bash)
-deploy:
+
+# Publish on PyPI
+jobs:
+  include:
+    - stage: build
+      python: 3.9
+      script: echo "Starting Pypi build"
+      deploy:
         provider: pypi
         username: __token__
+        distributions: "sdist bdist_wheel"
         password:
           secure: 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
         on:
           tags: true
           skip_existing: true
+
+# The password is encrypted with:
+# `cd prototorch && travis encrypt your-pypi-api-token --add deploy.password`
+# See https://docs.travis-ci.com/user/deployment/pypi and
+# https://github.com/travis-ci/travis.rb#installation
+# for more details
+# Note: The encrypt command does not work well in ZSH.