Merge branch 'ashmckenzie/golang-1-15' into 'main'

Add go:1.15 CI job

See merge request gitlab-org/gitlab-shell!439

.gitlab-ci.yml

@@ -60,9 +60,16 @@ go:1.14:
     - make coverage
   coverage: '/\d+.\d+%/'
 
+go:1.15:
+  extends: .test
+  image: golang:1.15
+  after_script:
+    - make coverage
+  coverage: '/\d+.\d+%/'
+
 race:
   extends: .test
-  image: golang:1.14
+  image: golang:1.15
   script:
     - make test_golang_race