added github actions workflow for automatic release

.github/workflows/release.yml

@@ -0,0 +1,46 @@
+name: pytest
+on:
+    push:
+    release:
+     types:
+       - published
+
+
+jobs:
+  build_sdist:
+    name: Build source distribution
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: '3.7'
+
+      - name: Build sdist
+        run: python setup.py sdist
+
+      - uses: actions/upload-artifact@v2
+        with:
+          path: dist/*.tar.gz
+
+
+  upload_pypi:
+    needs: [build_sdist]
+    runs-on: ubuntu-latest
+    # upload to PyPI on every tag starting with 'v'
+    #if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags/v')
+    # alternatively, to publish when a GitHub Release is created, use the following rule:
+    if: github.event_name == 'release' && github.event.action == 'published'
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: artifact
+          path: dist
+
+      - uses: pypa/gh-action-pypi-publish@master
+        with:
+          user: __token__
+          password: ${{ secrets.pypi_password }}
+          # To test: repository_url: https://test.pypi.org/legacy/