Try enabling a Mac M1 integration testing target for GHA builds

Author: pimterry

.github/workflows/ci.yml

@@ -91,6 +91,9 @@ jobs:
           - platform: Ubuntu 20.04
             os: "ubuntu-20.04"
             test-script: "./unix.sh linux"
+          - platform: MacOS 14 (M1)
+            os: "macos-14"
+            test-script: "./unix.sh darwin"
           - platform: MacOS 13
             os: "macos-13"
             test-script: "./unix.sh darwin"