fix(package): update bn.js to version 5.0.0

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
   "dependencies": {
     "bencode": "^2.0.0",
     "bittorrent-peerid": "^1.0.2",
-    "bn.js": "^4.4.0",
+    "bn.js": "^5.0.0",
     "compact2string": "^1.2.0",
     "debug": "^4.0.1",
     "ip": "^1.0.1",