chore: update variable group

 - add fine grained access token,
 - add email address

build-deploy-github-pages.yml

@@ -29,7 +29,7 @@ variables:
     value: amido.github.io
   - name: working_directory
     value: "$(Agent.BuildDirectory)/s/$(self_repo)"
-  - group: release-github-credentials
+  - group: stack-github-pages
 
 steps:
   - checkout: self