It works with fluidsynth 2.

Backported from r400: https://sourceforge.net/p/drumstick/code/400/

--- a/library/rt-backends/CMakeLists.txt
+++ b/library/rt-backends/CMakeLists.txt
@@ -54,1 +54,1 @@ if (PKG_CONFIG_FOUND)
-    pkg_check_modules(FLUIDSYNTH fluidsynth>=1.1.1 fluidsynth<=1.1.11)
+    pkg_check_modules(FLUIDSYNTH fluidsynth>=1.1.1)