Update snakeyaml from 1.18 to 1.26 due to 3rd party vulnerability issue CVE-2017-18640

Current Situation

• Currently JobScheduler engine use snakeyaml version 1.18
• a vulnerability affects this version,
  • see https://cve.mitre.org/cgi-bin/cvename.cgi?name=2017-18640

Desired Behavior

• Due to a vulnerability Issue of older snakeyaml releases the JobScheduler engine should use the current version 1.26 that fixes the issues.