Tune pypy version on OSX CI

Supposedly this will bring me great luck and good fortune!

Author: vidartf

.github/workflows/python-macos.yml

@@ -11,7 +11,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos]
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10-dev", "pypy3"]
+        python-version:
+          ["3.6", "3.7", "3.8", "3.9", "3.10-dev", "pypy-3.7-v7.3.3"]
     steps:
       - name: Checkout
         uses: actions/checkout@v2