dep: update go-libp2p

go.mod

 module github.com/libp2p/go-libp2p-pubsub
 
 require (
-	github.com/gogo/protobuf v1.2.1
+	github.com/gogo/protobuf v1.3.1
 	github.com/hashicorp/golang-lru v0.5.1
 	github.com/ipfs/go-log v0.0.1
-	github.com/libp2p/go-libp2p-blankhost v0.1.1
-	github.com/libp2p/go-libp2p-core v0.0.1
-	github.com/libp2p/go-libp2p-swarm v0.1.0
-	github.com/multiformats/go-multiaddr v0.0.4
+	github.com/libp2p/go-libp2p-blankhost v0.1.4
+	github.com/libp2p/go-libp2p-core v0.2.4
+	github.com/libp2p/go-libp2p-swarm v0.2.2
+	github.com/multiformats/go-multiaddr v0.1.1
 	github.com/multiformats/go-multistream v0.1.0
 	github.com/whyrusleeping/timecache v0.0.0-20160911033111-cfcb2f1abfee
 )