Add golangci-lint to CI job

This job is added per the documentation:
https://docs.gitlab.com/ee/development/go_guide/#automatic-linting

Add libkrb5-dev to golangci-lint job

This is needed to process internal/sshd/gssapi.go.

.gitlab-ci.yml

@@ -208,3 +208,18 @@ modules:tidy:
   script:
     - go mod tidy
     - git diff --exit-code go.mod go.sum
+
+lint:
+  image: golangci/golangci-lint
+  stage: test
+  script:
+    - apt update && apt install -y libkrb5-dev
+    # Write the code coverage report to gl-code-quality-report.json
+    # and print linting issues to stdout in the format: path/to/file:line description
+    # remove `--issues-exit-code 0` or set to non-zero to fail the job if linting issues are detected
+    - golangci-lint run --issues-exit-code 0 --print-issued-lines=false --out-format code-climate:gl-code-quality-report.json,line-number
+  artifacts:
+    reports:
+      codequality: gl-code-quality-report.json
+    paths:
+      - gl-code-quality-report.json