Build: Switch macos-13 (Intel) to macos-15-intel

Ref actions/runner-images#13046.

Cherry-picked from 84948ce (3.0.0-dev).

Stick with Intel on the stable-2.x branch, because we use an older
Puppeteer here that does not yet support ARM.

> npm WARN deprecated puppeteer@5.5.0:
> The chromium binary is not available for arm64

Author: Krinkle

.github/workflows/CI.yaml

@@ -52,7 +52,7 @@ jobs:
             script: npm run test-nolint
 
           - name: "macOS: Node 16"
-            os: macos-13
+            os: macos-15-intel
             node: 16.x
             script: npm run test-nolint