ci: add job to build release artifacts

.github/workflows/publish.yml

@@ -26,3 +26,35 @@ jobs:
         run: |
           poetry config pypi-token.pypi $PYPI_TOKEN
           poetry publish --build
+
+  build-release-artifacts:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: "3.8"
+
+      - name: Install prerequisites
+        run: |
+          python -m pip install --upgrade pip
+          pip install pyinstaller
+          pip install .
+
+      - name: Build distributable
+        run: |
+          pyinstaller pycgtool/__main__.py --name pycgtool-${{ matrix.os }} --onefile --collect-data mdtraj --hidden-import xdrlib
+
+      - uses: ncipollo/release-action@v1
+        with:
+          allowUpdates: true
+          artifact: dist/pycgtool-${{ matrix.os }}
+          token: ${{ secrets.GITHUB_TOKEN }}