use cocotb native tracing capability

[proppy]

couldn't we use https://docs.cocotb.org/en/stable/simulator_support.html#sim-verilator-waveforms instead of:

ttsky-verilog-template/test/tb.v

Lines 10 to 14 in 0ac027d

	initial begin
	$dumpfile("tb.vcd");
	$dumpvars(0, tb);
	#1;
	end

[urish]

I guess we could - could you please come up with a pull request?