Fix retworkx compat artifact CI job (#692)

Before pushing the 0.12.0 tag I noticed the CI configuration for the
retworkx release artifacts was broken and wouldn't run because of a
dependency on the rustworkx jobs that was defined in a separate
workflow. This commit updates the CI config by adding the retworkx
artifact job to the wheels workflow so we can express the dependency on
rustworkx being published first.

.github/workflows/wheels.yml

@@ -356,3 +356,27 @@ jobs:
         env:
           TWINE_PASSWORD: ${{ secrets.TWINE_PASSWORD }}
           TWINE_USERNAME: retworkx-ci
+    retworkx-compat-build:
+      name: Build retworkx
+      runs-on: ubuntu-latest
+      needs: ["build_wheels", "build-win32-wheels"]
+      steps:
+        - uses: actions/checkout@v2
+        - uses: actions/setup-python@v2
+          name: Install Python
+          with:
+            python-version: '3.7'
+        - name: Install deps
+          run: pip install -U twine setuptools-rust
+        - name: Build sdist
+          run: python setup.py sdist bdist_wheel
+          env:
+            RUSTWORKX_PKG_NAME: retworkx
+        - uses: actions/upload-artifact@v2
+          with:
+            path: ./dist/*
+        - name: Upload to PyPI
+          run: twine upload ./dist/*
+          env:
+            TWINE_PASSWORD: ${{ secrets.TWINE_PASSWORD }}
+            TWINE_USERNAME: retworkx-ci