CI: try testing on Apple Silicon (pysal#542)

Author: martinfleis

.github/workflows/tests.yaml

@@ -26,6 +26,8 @@ jobs:
         include:
           - environment-file: ci/envs/312-latest.yaml
             os: macos-latest
+          - environment-file: ci/envs/312-latest.yaml
+            os: macos-14 # Apple Silicon
           - environment-file: ci/envs/312-latest.yaml
             os: windows-latest
     defaults: