Changed parameter from 18 to 21

ch4/timebase.sv

@@ -1,6 +1,6 @@
 `timescale 1ns/1ps
 
-module timebase #(parameter N = 18) 
+module timebase #(parameter N = 21) 
    (input logic clk,
     input logic reset,
     output logic [N-1:0] count);

ch4/timebase_tb.sv

@@ -1,10 +1,10 @@
 `timescale 1ns/1ps
 
-module timebase_tb();
+module timebase_tb #(parameter N = 21);
 
    logic clk;
    logic reset;
-   logic [17:0] count;
+   logic [N-1:0] count;
    
    timebase test (clk, reset, count);