Add workflow for publishing to PyPI (#147)

* Add workflow for publishing to PyPI

* Add generation of GitHub release draft

Author: mcs07

.github/workflows/release.yml

@@ -0,0 +1,99 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    name: Build dists
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+        with:
+          version: "0.8.4"
+          enable-cache: true
+
+      - name: Verify tag matches project version
+        run: |
+          VER=$(uv version --short)
+          TAG=${GITHUB_REF_NAME#v}
+          test "$VER" = "$TAG" || { echo "Tag $TAG != version $VER"; exit 1; }
+
+      - name: Build sdist and wheel with uv
+        run: uv build --no-sources
+
+      - name: Upload dist artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: dist
+          path: dist/*
+
+  publish:
+    name: Publish to PyPI
+    needs: build
+    runs-on: ubuntu-latest
+    environment:
+      name: pypi
+      url: https://pypi.org/p/PubChemPy
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+      - name: Download dist artifacts
+        uses: actions/download-artifact@v4
+        with:
+          name: dist
+          path: dist
+
+      - name: Publish package distributions to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+
+  release:
+    name: Create GitHub Release
+    needs: publish
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Download dist artifacts
+        uses: actions/download-artifact@v4
+        with:
+          name: dist
+          path: dist
+
+      - name: Create GitHub Release (draft)
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG: ${{ github.ref_name }}
+        run: |
+          args=(
+            "${TAG}" dist/*
+            --title "PubChemPy ${TAG#v}"
+            --generate-notes
+            --draft
+          )
+          if gh release view "${TAG}" >/dev/null 2>&1; then
+            echo "Release ${TAG} already exists; skipping create."
+          else
+            gh release create "${args[@]}"
+          fi