chore: update deps

update to go-libp2p-core 0.6.0

go.mod

@@ -2,14 +2,14 @@ module github.com/libp2p/go-libp2p-discovery
 
 require (
 	github.com/hashicorp/golang-lru v0.5.4
-	github.com/ipfs/go-cid v0.0.5
-	github.com/ipfs/go-log v1.0.3
-	github.com/libp2p/go-libp2p-blankhost v0.1.4
-	github.com/libp2p/go-libp2p-core v0.5.1
-	github.com/libp2p/go-libp2p-peerstore v0.2.2
-	github.com/libp2p/go-libp2p-swarm v0.2.3
+	github.com/ipfs/go-cid v0.0.6
+	github.com/ipfs/go-log v1.0.4
+	github.com/libp2p/go-libp2p-blankhost v0.2.0
+	github.com/libp2p/go-libp2p-core v0.6.0
+	github.com/libp2p/go-libp2p-peerstore v0.2.6
+	github.com/libp2p/go-libp2p-swarm v0.2.8
 	github.com/multiformats/go-multihash v0.0.13
-	golang.org/x/sync v0.0.0-20190423024810-112230192c58
+	golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a
 )
 
 go 1.13