gx publish 4.0.0

This is to testify that go-libp2p-kad-dht last release (3.0.17)
contains breaking changes. Bumping the major version.

.gx/lastpubver

-3.0.17: QmPRvmyxE33XBQ7MSGg7u4qYgErBA8pMdWCnysShEcGpmG
+4.0.0: QmZcitfGoJ1JCwF9zdQvczfmwzLKugqtEGvTMXYcX23zbU

package.json

@@ -172,6 +172,6 @@
   "license": "MIT",
   "name": "go-libp2p-kad-dht",
   "releaseCmd": "git commit -a -m \"gx publish $VERSION\"",
-  "version": "3.0.17"
+  "version": "4.0.0"
 }