Add workflow to publish op PyPI

Author: skirpichev

.github/workflows/publish.yml

@@ -0,0 +1,34 @@
+name: Publish on PyPI
+on: push
+jobs:
+  build:
+    name: Build distribution
+    runs-on: ubuntu-22.04
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+      with:
+        python-version: 3.13
+    - run: pip install build
+    - run: python -m build -s
+    - uses: actions/upload-artifact@v4
+      with:
+        name: python-gmp
+        path: dist/
+  publish-to-pypi:
+    name: Publish distribution to PyPI
+    if: startsWith(github.ref, 'refs/tags/')
+    needs:
+      - build
+    runs-on: ubuntu-22.04
+    environment:
+      name: pypi
+      url: https://pypi.org/p/python-gmp
+    permissions:
+      id-token: write
+    steps:
+    - uses: actions/download-artifact@v4
+      with:
+        name: python-gmp
+        path: dist/
+    - uses: pypa/gh-action-pypi-publish@release/v1