feat: Add version check before publishing to PyPI

Author: eddiegulay

.github/workflows/publish.yml

@@ -30,7 +30,21 @@ jobs:
         run: |
           python -m build
 
+      - name: Check if version exists on PyPI
+        id: check-version
+        run: |
+          PKG_NAME=$(python3 -c "import toml; print(toml.load('pyproject.toml')['project']['name'])")
+          PKG_VERSION=$(python3 -c "import toml; print(toml.load('pyproject.toml')['project']['version'])")
+          EXISTS=$(curl -s https://pypi.org/pypi/$PKG_NAME/json | grep -o "\"$PKG_VERSION\"")
+          if [ "$EXISTS" != "" ]; then
+            echo "Version $PKG_VERSION already exists on PyPI. Skipping upload."
+            echo "skip_upload=true" >> $GITHUB_OUTPUT
+          else
+            echo "skip_upload=false" >> $GITHUB_OUTPUT
+          fi
+
       - name: Publish to PyPI
+        if: steps.check-version.outputs.skip_upload != 'true'
         env:
           TWINE_USERNAME: __token__
           TWINE_PASSWORD: ${{ secrets.PYPI_API_TOKEN }}