Update testing.yml

Author: MMathisLab

.github/workflows/testing.yml

@@ -18,6 +18,10 @@ jobs:
         exclude:
           - os: windows-latest
             python-version: "3.10"
+          - os: windows-latest
+            python-version: "3.9"
+          - os: macos-latest
+            python-version: "3.9"
         include:
           - os: ubuntu-latest
             path: ~/.cache/pip