Update to fluidsynth 2.1.3

[MaxPayne86]

Hello,

https://github.com/MaxPayne86/meta-moddevices-contrib/blob/dunfell-hotfix-1.11/recipes-plugins/fluidsynth-plug/fluidsynth-plug.bb

I would like to switch to fluidsynth version contained in meta-openembedded dunfell branch which contains some interesting patches like

0003-Use-ARM-NEON-accelaration-for-float-multithreaded-se.patch

keep up with the good work, thanks a lot!