Update check.yml

Adding a command to list CPU details on macOS runners. Hopefully this will illuminate why their runners intermittently fail due to incompatible CPU instruction sets

.github/workflows/check.yml

@@ -22,6 +22,9 @@ jobs:
           - 3.9
           - 3.8
     steps:
+      - name: Print agent CPU info
+        if: runner.os == 'macOS'
+        run: sysctl -a machdep.cpu
       - name: Setup Python
         uses: actions/setup-python@v4
         with:
@@ -46,4 +49,4 @@ jobs:
         run: tox --skip-pkg-install
         env:
           CI_RUN: "yes"
-          DIFF_AGAINST: HEAD
+          DIFF_AGAINST: HEAD