updating yamato to use stable tag for upm-ci-utils

.yamato/promote.yml

     UPMCI_PROMOTION: 1
   commands:
     - git submodule update --init --recursive
-    - npm install upm-ci-utils -g --registry {{ upmci_registry }}
+    - npm install upm-ci-utils@stable -g --registry {{ upmci_registry }}
     - upm-ci package test -u {{ editor.version }} --package-path ./com.unity.perception --type vetting-tests
   artifacts:
     logs:

.yamato/upm-ci-full.yml

     flavor: b1.large
   commands:
      - git submodule update --init --recursive
-     - npm install upm-ci-utils -g --registry {{ upmci_registry }}
+     - npm install upm-ci-utils@stable -g --registry {{ upmci_registry }}
      - upm-ci package pack --package-path ./com.unity.perception/
   artifacts:
     packages:
     flavor: {{ platform.flavor}}
   commands:
     - git submodule update --init --recursive
-    - npm install upm-ci-utils -g --registry {{ upmci_registry }}
+    - npm install upm-ci-utils@stable -g --registry {{ upmci_registry }}
     - upm-ci package test -u {{ editor.version }} --package-path ./com.unity.perception --type vetting-tests
   artifacts:
     logs: