API: Update num-complex to 0.4

Author: bluss

Cargo.toml

@@ -28,7 +28,7 @@ test = true
 [dependencies]
 num-integer = { version = "0.1.39", default-features = false }
 num-traits = { version = "0.2", default-features = false }
-num-complex = { version = "0.3", default-features = false }
+num-complex = { version = "0.4", default-features = false }
 
 # Use via the `rayon` crate feature!
 rayon_ = { version = "1.0.3", optional = true, package = "rayon" }