How to deploy GCP functions with Golang 1.15

Hi,

Is this possible to deploy GCP functions with Golang 1.15 (or at least 1.14) with Serverless ? This doesn’t work using runtime: 115 :

(serverless.yml)
...
provider:
  name: google
  runtime: go115
...
{"ResourceType":"gcp-types/cloudfunctions-v1:projects.locations.functions","ResourceErrorCode":"400","ResourceErrorMessage":{"code":400,"message":"The request has errors","status":"INVALID_ARGUMENT","details":[{"@type":"type.googleapis.com/google.rpc.BadRequest","fieldViolations":[{"field":"runtime","description":"Invalid runtime."}]}],"statusMessage":"Bad Request","requestPath":"https://cloudfunctions.googleapis.com/v1/projects/**************/locations/us-central1/functions/*****","httpMethod":"PATCH"}}

And it looks like 1.15 is already available :

Thanks.