fix: allow negative values for rotating filter

src/filters.rs

@@ -23,6 +23,10 @@ impl PassThroughFilter {
 			PassThroughFilter::Rotating(filter_angle) => {
 				let mut hsla = color.as_hsla_f32();
 				hsla[0] = (hsla[0] + filter_angle) % 360.;
+				// floating rem is not modulo!
+				if hsla[0] < 0. {
+					hsla[0] += 360.;
+				}
 				Color::hsla(hsla[0], hsla[1], hsla[2], hsla[3])
 			}
 		}