Add GitHub action to deploy to PyPI

.github/workflows/deploy.yml

@@ -0,0 +1,39 @@
+name: Deploy to PyPI
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -U setuptools wheel twine build
+
+      - name: Build
+        run: |
+          python -m build .
+
+      - name: Check that package version matches git tag ${{ github.ref_name }}
+        shell: bash
+        run: |
+          ls -l dist
+          test -f "dist/stardist-napari-${{ github.ref_name }}.tar.gz"
+          test -f "dist/stardist_napari-${{ github.ref_name }}-py3-none-any.whl"
+
+      - name: Publish to PyPI
+        env:
+          TWINE_USERNAME: __token__
+          TWINE_PASSWORD: ${{ secrets.PYPI_API_TOKEN }}
+        run: |
+          twine upload --verbose dist/*