Discv5

Discv5 is used at run time in 3 crates.

Number of dependers	Discv5 version	Downloads/month
0	0.6.0	9.0K
0	0.4.1	13K
2	0.3.1	16
1	0.2.2	52

Depender			Discv5 version
		ethportal-api		^0.3.1
		discv5-cli		^0.3.0
		trin-types		^0.2.1