SSL certificate problem: self signed certificate in certificate chain

Hello,

I have deployed gitlab runner in Kubernetes cluster by using this chart gitlab/gitlab-runner. Here is the configuration about runner :

    [[runners]]
      [runners.kubernetes]
        namespace = "{{.Release.Namespace}}"
        helper_image = "***/gitlab-runner-helper:x86_64-${CI_RUNNER_REVISION}"
        cpu_limit = "200m"
        memory_limit = "256Mi"
        cp_requests = "100m"
        memory_requests = "128Mi"
        helper_cpu_limit = "200m"
        helper_memory_limit = "256Mi"
        helper_cp_requests = "100m"
        helper_memory_requests = "128Mi"

When I run the pipeline based on this runner, we have this error

Getting source from Git repository 00:01
Fetching changes with git depth set to 20...
Initialized empty Git repository in /builds/xx-bi/xx/xx.git/
Created fresh repository.
fatal: unable to access 'https://gitlab.xxx.fr/xx-bi/xx/xx.git/': SSL certificate problem: self signed certificate in certificate chain

do you have some ideas pls?

thanks