Fixed bug in adder/subtracter where code assuming width was the bit width was not updated when moving to the 2**N approach required by the assignment. Updated adder/subtracter testbench to correctly instantiate the asser/subtracter and removed unused variable

tests/asu_tb.sv

@@ -10,10 +10,8 @@ module asu_tb #(width=8)();
     logic [width-1:0] C_exp;
     logic [0:0] Cout_exp;
     logic [0:0] Cin_exp;   // TODO
-    
-    logic [0:0] Signed_overflow;
 
-    asu #(width) dut(op, A, B, C, Cout, Cin);
+    asu #($clog2(width)) dut(op, A, B, C, Cout, Cin);
 
     integer error_count;
     initial begin