update upm-ci-utils source (#3811)

.yamato/com.unity.ml-agents-pack.yml

     image: package-ci/ubuntu:stable
     flavor: b1.large
   commands:
-    - npm install upm-ci-utils@stable -g --registry https://api.bintray.com/npm/unity/unity-npm
+    - npm install upm-ci-utils@stable -g --registry https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-npm
     - upm-ci package pack --package-path com.unity.ml-agents
   artifacts:
     packages:

.yamato/com.unity.ml-agents-test.yml

     image: {{ platform.image }}
     flavor: {{ platform.flavor}}
   commands:
-    - npm install upm-ci-utils@stable -g --registry https://api.bintray.com/npm/unity/unity-npm
+    - npm install upm-ci-utils@stable -g --registry https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-npm
     - upm-ci package test -u {{ editor.version }} --package-path com.unity.ml-agents {{ editor.coverageOptions }}
     - python ml-agents/tests/yamato/check_coverage_percent.py upm-ci~/test-results/ {{ editor.minCoveragePct }}
   artifacts: