Use NEXUS_NPM_CONFIG env var for publishing in gitlab ci.

1 job for 3.2.1 in 17 seconds
Status Name Job ID Coverage
failed publish #64956


Name Stage Failure
publish Publish
npm notice total files:   9                                       
npm notice
npm ERR! publish Failed PUT 403
npm ERR! code E403
npm ERR! 403 Forbidden

npm ERR! A complete log of this run can be found in:
npm ERR! /root/.npm/_logs/2019-09-24T10_49_16_521Z-debug.log
ERROR: Job failed: exit code 1