Add GH action to build and publish package (#1)

.github/workflows/on_tag.yml

@@ -0,0 +1,29 @@
+name: Publish sdist tarball to PyPi
+
+on:
+  push:
+    tags:
+        - "*"
+
+jobs:
+  build-n-publish:
+    name: Build and publish on PyPI
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v5
+        with:
+          python-version: 3.9
+      - name: Build a source tarball
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install build
+      - name: Build a source tarball
+        run: |
+          python -m build
+      - name: Publish distribution package to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          password: ${{ secrets.PYPI_API_TOKEN }}
+          verbose: true