What is the right way to add ssh keys for npm packages the pull directly from github (package.json)?

Downloading 'node-v8.8.1-linux-x64.tar.gz'[===========================] 100%
npm --cache-min=Infinity install
The authenticity of host 'github.com (' can't be established.
RSA key fingerprint is SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8.
Are you sure you want to continue connecting (yes/no)? [ .................] [ .................] \ loadIdealTree:loadAllDepsIntoIdealTree: sill install
npm ERR! Error while executing:
npm ERR! /usr/bin/git ls-remote -h -t ssh://git@github.com/my/repo.git
npm ERR!
npm ERR! Host key verification failed.
npm ERR! fatal: Could not read from remote repository.
npm ERR!
npm ERR! Please make sure you have the correct access rights
npm ERR! and the repository exists.