CI: Drop set-output, upgrade gh-action-pypi-publish to 1.5.1

Author: effigies

.github/workflows/pythonpackage.yml

@@ -109,10 +109,10 @@ jobs:
       if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
       env:
         PYPI_API_TOKEN: "${{ secrets.PYPI_API_TOKEN }}"
-      run: if [ -n "$PYPI_API_TOKEN" ]; then echo ::set-output name=DEPLOY::true; fi
+      run: if [ -n "$PYPI_API_TOKEN" ]; then echo "DEPLOY=true" >> $GITHUB_OUTPUT; fi
     - name: Upload to PyPI
       if: steps.deployable.outputs.DEPLOY
-      uses: pypa/gh-action-pypi-publish@27b31702a0e7fc50959f5ad993c78deac1bdfc29  # v1.4.2
+      uses: pypa/gh-action-pypi-publish@37f50c210e3d2f9450da2cd423303d6a14a6e29f  # v1.5.1
       with:
         user: __token__
         password: ${{ secrets.PYPI_API_TOKEN }}