chore(deps): update golang docker tag to v1.15

.gitlab-ci.yml

@@ -16,7 +16,7 @@ build_pkg:bullseye:amd64:
 
 test:
   stage: test
-  image: golang:1.14
+  image: golang:1.15
   script:
     - go test -v -cover -coverprofile=cover.out ./...
     - go get github.com/boumenot/gocover-cobertura