Update continuous-build.yml (#97)

the latest macos-14 supports arm only. 
This PR using the previous version of macos image to unblock the release.

Author: wangzlei

.github/workflows/continuous-build.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-latest
+          - macos-13
           - ubuntu-latest
         ruby:
           - 2.4