www/h2o: patch for HTTP2 rapid reset attack, deprecate

• downstream dnsdist project has backported a fix for this specific issue
• deprecation is still planned, and port should not be considered secure
• pet port in line with www/h2o-devel

See https://github.com/h2o/h2o/pull/3293 for further details

Obtained from: Remi Gacogne <remi.gacogne@powerdns.com>
Security: CVE-2023-44487
Security: https://github.com/h2o/h2o/security/advisories/GHSA-2m7v-gc89-fjqf

(cherry picked from commit dcd7c23bd4dd801ec1a5a415612a66cb97032dde)