Update buildspecs for GenerateJavadocs with apt-key add

Author: davidh44

release-resources/buildspecs/generate-java-docs.yml

@@ -6,6 +6,7 @@ phases:
     runtime-versions:
       java: "$JAVA_RUNTIME"
     commands:
+      - curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
       - apt-get update
       - pip install awscli --upgrade --user
       - pip install rsa