www/librespeed: Update to 5.2.2

Changelog

• Improved auto test duration formula
• Minor changes

PR: 249958
Submitted by: Dries Michiels <driesm.michiels@gmail.com> (maintainer)
Approved by: tcberner (mentor)
Relnotes: https://github.com/librespeed/speedtest/releases/tag/5.2.2
Differential Revision: https://reviews.freebsd.org/D26579