Upgrade Go to 1.21.1

.gitlab/ci/Dockerfile

-FROM golang:1.13.15-alpine3.12
+FROM golang:1.21.1-alpine3.18
 
 # Force build - 2022-10-03T17:42:00+0000
 RUN apk add --no-cache make git py-pip bash curl && \

.gitlab/ci/yaml/_common.gitlab-ci.yml

 variables:
   USE_CONTAINER: "true"
-  CI_IMAGE: registry.gitlab.com/gitlab-org/ci-cd/docker-machine/ci:go1.13.15-alpine3.12-1
+  CI_IMAGE: registry.gitlab.com/gitlab-org/ci-cd/docker-machine/ci:go1.21.1-alpine3.18
   DOCKER_VERSION: "20.10.12"
 
 default: