Add GitLab CI config

.gitlab-ci.yml

+---
+
+image: debian:buster
+
+variables:
+  GOCACHE: $CI_PROJECT_DIR/.gocache
+  GOPATH: $CI_PROJECT_DIR/.go
+
+cache:
+  paths:
+    - .gocache
+    - .go
+
+before_script:
+  - echo 'deb http://deb.debian.org/debian buster-backports main' > /etc/apt/sources.list.d/backports.list
+  - apt-get update && apt-get -qq -y -t buster-backports install golang git
+  - go version
+
+build:
+  script:
+    - go build -o $CI_PROJECT_NAME-$GOOS-$GOARCH
+  artifacts:
+    paths:
+      - $CI_PROJECT_NAME-$GOOS-$GOARCH
+  parallel:
+    matrix:
+      - GOOS:
+          - linux
+        GOARCH:
+          - amd64
+          - arm