Add aarch64 wheel build support

.github/workflows/cibuildwheels.yml

@@ -21,12 +21,12 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        arch: [x86, amd64]
+        arch: [auto, aarch64]
         exclude:
-          - os: ubuntu-latest
-            arch: x86
+          - os: windows-latest
+            arch: aarch64
           - os: macos-latest
-            arch: x86
+            arch: aarch64
 
     steps:
       - name: Checkout repo
@@ -39,6 +39,10 @@ jobs:
         with:
           python-version: '3.7'
 
+      - name: Set up QEMU
+        if: ${{ matrix.arch == 'aarch64' }}
+        uses: docker/setup-qemu-action@v1
+
       - name: Install Ninja
         uses: seanmiddleditch/gha-setup-ninja@master
 
@@ -54,7 +58,7 @@ jobs:
           python -m pip install -r requirements-tests.txt
 
       - name: Build wheels (Windows x86)
-        if: ${{ runner.os == 'Windows' && matrix.arch == 'x86'}}
+        if: ${{ runner.os == 'Windows' }}
         run: |
           python -m pip install --upgrade pip
           python -m pip install cibuildwheel
@@ -72,7 +76,7 @@ jobs:
           arch: amd64
 
       - name: Build wheels (Windows / amd64)
-        if: ${{ runner.os == 'Windows' && matrix.arch == 'amd64'}}
+        if: ${{ runner.os == 'Windows' }}
         run: |
           python -m pip install --upgrade pip
           python -m pip install cibuildwheel
@@ -93,6 +97,7 @@ jobs:
         env:
           CIBW_BUILD: 'cp37-* cp38-* cp39-*'
           CIBW_SKIP: '*-manylinux*_i686'
+          CIBW_ARCHS_LINUX: ${{ matrix.arch }}
           CIBW_BEFORE_BUILD: python -m pip install -r requirements.txt
           CIBW_BEFORE_TEST: python -m pip install -r requirements-tests.txt
           CIBW_TEST_COMMAND: python -m pytest {project}/tests