build: drop support for Go 1.17
We've been running on Go 1.18 since %15.6 (https://gitlab.com/gitlab-org/build/CNG/-/blob/15-6-stable/ci_files/variables.yml#L19), so we can safely drop support for the already unsafe 1.17.
Edited by João Pereira
We've been running on Go 1.18 since %15.6 (https://gitlab.com/gitlab-org/build/CNG/-/blob/15-6-stable/ci_files/variables.yml#L19), so we can safely drop support for the already unsafe 1.17.