audio/cava: Update to 0.7.3

Update from 0.7.1 to 0.7.3 brings several improvements and
bug fixes[1][2]. More important ones are:

• Fix install on macos
• ncurses mode is now default again
• Improved portaudio audio input
• Added Hann windowing and proper ring buffer

[1] https://github.com/karlstav/cava/releases/tag/0.7.3
[2] https://github.com/karlstav/cava/releases/tag/0.7.2

PR: 250862
Submitted by: Adam Jimerson <vendion@gmail.com> (takes maintainership)
Approved by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D27091