Security update for google-cloud-sap-agent

This update for google-cloud-sap-agent fixes the following issue: CVE-2026-39821: golang.org/x/net/idna: failure to reject ASCII-only Punycode-encoded labels allows for validation bypass and privilege escalation bsc1266604. Changes for google-cloud-sap-agent: Update golang.org/x/net to v0.57.0...