Update deploy-pypi.yml (#391)

This is copy-pasted from https://github.com/aiqm/torchani/blob/master/.github/workflows/deploy-test-pypi.yml but I forgot to update it...

We should use the tag created on GitHub, not add a new tag named after date

.github/workflows/deploy-pypi.yml

@@ -28,6 +28,5 @@ jobs:
     - name: Deploy
       run: |
         rm -rf dist/*
-        git tag $(date +'v%Y.%m.%d.%H.%M.%S')
         python setup.py bdist bdist_wheel
         twine upload -u zasdfgbnm-bot -p ${{secrets.zasdfgbnm_bot_pypi_password}} dist/*