The simplest way is to tag the repo with the appropriate version tag and let gitlab's CI do the rest.
Don't forget to also increase the chart version in mlflow/Chart.yaml
Prerequisites:
# the access token requires api scope
helm repo add --username $GITLAB_USER --password $GITLAB_ACCESS_TOKEN mondata-mlflow https://gitlab.mondata.de/api/v4/projects/113/packages/helm/stable
helm plugin install https://github.com/chartmuseum/helm-push.git
Performing the release:
helm package mlflow
helm cm-push mlflow-$CHART_VERSION.tgz mondata-mlflow