Use cibuildwheel to build wheels.

This will enable the building of macOS ARM64 compatible wheels, fixing ultrajson#456 (and
also lets us delete lots of code!!!).

.github/workflows/deploy-wheels.yml

@@ -0,0 +1,64 @@
+name: Deploy wheels
+
+on:
+  push:
+    branches:
+      - main
+  release:
+    types:
+      - published
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [windows-latest, macOS-latest, ubuntu-latest]
+        linux-arch: ['auto']
+        include:
+          - os: "ubuntu-latest"
+            linux-arch: "aarch64"
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+
+      - name: Install cibuildwheel
+        run: python -m pip install cibuildwheel==2.3.0
+
+      - name: Build wheels
+        run: python -m cibuildwheel --output-dir dist
+        # Options are supplied via environment variables:
+        env:
+          # Build separate wheels for macOS's different architectures.
+          CIBW_ARCHS_MACOS: "x86_64 arm64"
+          # Build only the currently selected Linux architecture (so we can
+          # parallelise for speed).
+          CIBW_ARCHS_LINUX: "${{ martix.linux-arch }}"
+          # Don't build with prerelease Python versions.
+          CIBW_PROJECT_REQUIRES_PYTHON: ">=3.6,<3.11"
+          # Testing
+          CIBW_TEST_REQUIRES: "pytest"
+          CIBW_TEST_COMMAND: pytest {package}/tests
+
+    - name: Upload as build artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: wheels
+        path: dist/*.whl
+
+    - name: Publish package to PyPI
+      if: github.event.action == 'published'
+      env:
+        TWINE_USERNAME: __token__
+        TWINE_PASSWORD: ${{ secrets.pypi_password }}
+      run: twine upload --skip-existing dist/*.whl
+
+    - name: Publish package to TestPyPI
+      if: github.repository == 'ultrajson/ultrajson'
+      env:
+        TWINE_USERNAME: __token__
+        TWINE_PASSWORD: ${{ secrets.test_pypi_password }}
+      run: |
+        twine upload --repository-url https://test.pypi.org/legacy/ --skip-existing dist/*.whl