Update hrtf lib to 0.8.1 - contains performance improvement

Author: orottier

Cargo.toml

@@ -22,7 +22,7 @@ cubeb = { version = "0.10", optional = true }
 dasp_sample = "0.11"
 float_eq = "1.0"
 hound = "3.5"
-hrtf = "0.8"
+hrtf = "0.8.1"
 llq = "0.1.1"
 log = "0.4"
 num-complex = "0.4"