build: bump go version to 1.16
go 1.15 is now EOL and it can be dropped safely since gitlab 14.2 has been released (according to the current policy: https://docs.gitlab.com/ee/development/go_guide/#supporting-multiple-go-versions)
status:
go version (latest): 1.17.0
version (additional): 1.16.7
Gitlab Version: master
CNG version: master (go 1.16.4)
Omnibus-builder image revision: 1.6.0 (go 1.16.4)
Gitlab Version: v14.2.0-ee
CNG version: v14.2.0-ee (go 1.16.4)
Omnibus-builder image revision: 1.6.0 (go 1.16.4)
Gitlab Version: v14.1.0-ee
CNG version: v14.1.0-ee (go 1.16.4)
Omnibus-builder image revision: 1.6.0 (go 1.16.4)
Gitlab Version: v14.0.0-ee
CNG version: v14.0.0-ee (go 1.16.4)
Omnibus-builder image revision: 1.6.0 (go 1.16.4)