Replace FreeBSD 13.0 with 11.4 (#692)
Replace FreeBSD 13.0 with 11.4 (#692)

13.0 hasn't been released yet and the CI build keeps failing for long.
FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth