audio/exhale: Update to 1.0.8

From the changelog[1]:

• minor quality improvements at low and high rates, some license text clarifications
• exhaleApp: slightly improved loudness calculation for low and high sampling rates
• exhaleLib: improved audio quality a bit for the lower and higher-rate CVBR modes
• License: removed references to BSD text, clarified disclaimer and contributor text

[1] https://gitlab.com/ecodis/exhale/-/releases/v1.0.8

PR: 250748
Submitted by: Daniel Engberg <daniel.engberg.lists@pyret.net> (maintainer)
Approved by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D27051