www/grafana8: Update to 8.5.21 (Fixes security vulnerabilities)

ChangeLog:
https://grafana.com/blog/2023/02/28/grafana-security-release-new-versions-with-security-fixes-for-cve-2023-0594-cve-2023-0507-and-cve-2023-22462/

PR: 269903
Reported by: drtr0jan@yandex.ru (maintainer)
MFH: 2023Q1 (security fix)
Security: CVE-2023-0594 CVE-2023-0507 CVE-2023-22462

(cherry picked from commit 5877f73ba26bbcb03700ab3d7d3943e9d0e0f3f3)