Revert "Fix travis warning"

There seems to be a problem with Travis and the handling of 'skip_cleanup' and 'cleanup'.

> Preparing deploy
>
> Cleaning up git repository with `git stash --all`. If you need build artifacts for
> deployment, set `deploy.skip_cleanup: true`. See
> https://docs.travis-ci.com/user/deployment#Uploading-Files-and-skip_cleanup.
>
> Saved working directory and index state WIP on (no branch): ...

This reverts commit 239c7a9.

Author: c00kiemon5ter

.travis.yml

@@ -68,7 +68,7 @@ jobs:
         - provider: pypi
           distributions: sdist bdist_wheel
           server: "https://test.pypi.org/legacy/"
-          cleanup: false
+          skip_cleanup: true
           username: "__token__"
           password: "$PYPI_PRE_RELEASE_TOKEN"
           on: