Allow lint step to fail

This way we can use the linter in all branches already and gradually
adjust our code to the new linter.

.gitlab-ci.yml

@@ -37,6 +37,7 @@ golangci-lint:
   image: golangci/golangci-lint:latest
   script:
     - make golangci-lint
+  allow_failure: true
 
 test:
   stage: test