Log warning if SIP is disabled and CLI version is < 2.15.1 (#2261)

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

Prior to CLI v2.15.1, MacOS 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.

* Log a warning if SIP is disabled and CLI is < 2.15.1

* Add changenote for SIP-disabled support on old CLI versions

* Set up Python 3.11 for all MacOS checks

.github/workflows/__test-proxy.yml

@@ -39,7 +39,7 @@ jobs:
       - name: Setup Python on MacOS
         uses: actions/setup-python@v5
         if: >-
-          matrix.os == 'macos-latest' && (
+          runner.os == 'macOS' && (
 
           matrix.version == 'stable-20230403' ||