update core so we can run it

sdk/core/ci.yml

@@ -41,8 +41,8 @@ pr:
       - '*.md'
       - /**/*.md
 
-stages:
-  - template: ../../eng/pipelines/templates/stages/archetype-sdk-client.yml
+extends:
+    template: ../../eng/pipelines/templates/stages/archetype-sdk-client.yml
     parameters:
       ServiceDirectory: core
       # CI has static code analysis disabled, while LiveTest will have it enabled