Update default node version from 14.x to 16.x in Ruby and .NetCore buildpacks
Update default node version from 14.x to 16.x in Ruby and .NetCore buildpacks

cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci