Try downgrading MacOS versions.

Author: timspainNERSC

.github/workflows/test_suite.yml

@@ -184,7 +184,7 @@ jobs:
 
   # Serial tests on latest Mac OS
   test-mac-serial:
-    runs-on: macos-latest
+    runs-on: macos-14
     timeout-minutes: 10
     steps:
     - uses: actions/checkout@v2