Docker images:
- GKE/GCE: gcr.io/endpoints-release/endpoints-runtime:2.55.4
- Cloud Run: gcr.io/endpoints-release/endpoints-runtime-serverless:2.55.4
Changes from release 2.55.3:
- change glibc version to 1.26.4 (#1018)
- Update version to 2.55.4 and owners. (#1020)
