travis: Remove pypy3 support\n\nDue to https://github.com/travis-ci/travis-ci/issues/6277 pypy3 can no longer be used and must be removed.
travis: Remove pypy3 support\n\nDue to https://github.com/travis-ci/travis-ci/issues/6277 pypy3 can no longer be used and must be removed.

polysquare/polysquare-ci-scripts,polysquare/polysquare-ci-scripts