package/fluidsynth: bump to version 2.1.2

Changes since v2.1.1:
https://github.com/FluidSynth/fluidsynth/releases/tag/v2.1.2


- fluidsynth now exits with error when user-provided command-line arguments are out-of-range
- add verbose error logging to opensles and oboe drivers
- fix a memory leak in oboe driver
- fix a NULL dereference in the fluidsynth commandline program

./utils/test-pkg --package fluidsynth
6 builds, 1 skipped, 0 build failed, 0 legal-info failed

Signed-off-by: Julien Olivain <juju@cotds.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>