This is just a warning, ES should start fine, just with a warning about seccomp not being available.
Elasticsearch security module tries to revoke Linux process privileges to reduce so called "attack vector" for malevolent activities, but your Linux kernel is either too old or not able to offer that process privilege revoke API.
Here's the related issue: https://github.com/elastic/elasticsearch/pull/13753
I think you can set bootstrap.seccomp=false in the yml file to disable this.