Update to latest cibuildwheel release.

QuLogic · QuLogic · commit 6b1f1edc9c0b · 2020-10-19T23:05:18.000-04:00
While that adds 3.9 support, we currently will skip it until NumPy
releases its wheels.
diff --git a/.github/workflows/cibuildwheel.yml b/.github/workflows/cibuildwheel.yml
@@ -28,7 +28,7 @@ jobs:
 
       - name: Install cibuildwheel
         run: |
-          python -m pip install cibuildwheel==1.5.5
+          python -m pip install cibuildwheel==1.6.3
 
       - name: Copy setup.cfg to configure wheel
         run: |
@@ -39,7 +39,7 @@ jobs:
           python -m cibuildwheel --output-dir dist
         env:
           CIBW_BUILD: "cp3?-*"
-          CIBW_SKIP: "cp35-* cp36-*"
+          CIBW_SKIP: "cp35-* cp36-* cp39-*"
           CIBW_MANYLINUX_X86_64_IMAGE: manylinux1
           CIBW_MANYLINUX_I686_IMAGE: manylinux1
           CIBW_BEFORE_BUILD: pip install certifi numpy==1.16
