Removed trailing whitespace

source/chacha20.d

@@ -316,7 +316,7 @@ ubyte[64] chacha20Exp(in ubyte[32] key, in ubyte[16] n) @safe pure nothrow @nogc
                                        sigma2,
                                        sigma3,
                                        key,
-                                       n));    
+                                       n));
 }
 
 @safe unittest