ci: cache, build wheels on macOS PyPy3

.github/workflows/ci.yml

@@ -57,6 +57,19 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
 
+    - name: Cache wheels
+      if: startsWith(runner.os, 'macOS')
+      uses: actions/cache@v2
+      with:
+        # This path is specific to macOS - we really only need it for PyPy NumPy wheels
+        # See https://github.com/actions/cache/blob/master/examples.md#python---pip
+        # for ways to do this more generally
+        path: ~/Library/Caches/pip
+        # Look to see if there is a cache hit for the corresponding requirements file
+        key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-
+
     - name: Prepare env
       run: python -m pip install -r tests/requirements.txt
 

tests/requirements.txt

 --extra-index-url https://antocuni.github.io/pypy-wheels/manylinux2010/
 numpy; platform_python_implementation!="PyPy" or sys_platform!="darwin" or python_version<"3.0"
+numpy<1.19; platform_python_implementation=="PyPy" and sys_platform=="darwin" and python_version>="3.0"
 pytest