fix(package): update async to version 3.0.1 (#481)

Author: greenkeeper[bot]

package.json

@@ -36,7 +36,7 @@
   },
   "homepage": "https://github.com/ipfs/interface-ipfs-core#readme",
   "dependencies": {
-    "async": "^2.6.1",
+    "async": "^3.0.1",
     "bl": "^3.0.0",
     "bs58": "^4.0.1",
     "chai": "^4.2.0",