PR Checks: use macos-12 runners for CLI v. < 2.15.1

Prior to CLI v2.15.1, ARM runners were not supported by the build tracer. "macos-latest" is now an ARM runner, so we run these tests on the old CLIs on Intel runners instead.

Author: angelapwen

.github/workflows/__diagnostics-export.yml

@@ -65,10 +65,18 @@ def writeHeader(checkStream):
                             if image.startswith(operatingSystem)]
 
         for runnerImage in runnerImages:
-            matrix.append({
-                'os': runnerImage,
-                'version': version
-            })
+            # Prior to CLI v2.15.1, ARM runners were not supported by the build tracer.
+            # "macos-latest" is now an ARM runner, so we run tests on the old CLIs on Intel runners instead.
+            if version in ["stable-20230403", "stable-v2.13.4", "stable-v2.13.5", "stable-v2.14.6"] and runnerImage == "macos-latest":
+                matrix.append({
+                    'os': "macos-12",
+                    'version': version
+                })
+            else:     
+                matrix.append({
+                    'os': runnerImage,
+                    'version': version
+                })
 
         useAllPlatformBundle = "false" # Default to false
         if checkSpecification.get('useAllPlatformBundle'):