Add linux aarch64 wheel support

.github/workflows/build-linux.yml

@@ -74,3 +74,52 @@ jobs:
         with:
           name: wheels
           path: ./wheelhouse
+
+  build_wheels_aarch64:
+    name: Build wheels on ${{ matrix.os }}, ${{ matrix.arch }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-18.04]
+        arch: [aarch64]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-python@v1
+        name: Install Python 3.8
+        with:
+          python-version: "3.8"
+
+      - name: Install cibuildwheel
+        run: |
+          python -m pip install cibuildwheel~=1.8.0
+
+      - uses: docker/setup-qemu-action@v1
+        name: Set up QEMU
+
+      - name: Checkout submodules
+        shell: bash
+        run: |
+          git submodule sync --recursive
+          git submodule update --init --force --recursive --depth=1
+
+      - name: Build wheel
+        if: contains(github.ref, 'tags/')
+        run: |
+          python -m cibuildwheel --output-dir wheelhouse
+        env:
+          CIBW_BUILD: cp36-* cp37-* cp38-* cp39-*
+          CIBW_ARCHS_LINUX: ${{ matrix.arch }}
+          CIBW_BEFORE_BUILD: python -m pip install --upgrade pip
+            && python -m pip install tox
+          CIBW_TEST_REQUIRES: tox
+          CIBW_TEST_COMMAND: cd /project
+            && python -m pip install -r requirements-dev.txt
+            && /opt/python/*/bin/tox -e py
+
+      - uses: actions/upload-artifact@v1
+        if: contains(github.ref, 'tags/')
+        with:
+          name: wheels
+          path: ./wheelhouse