fix(package): update ipfs-mfs to version 0.12.0 (#2275)

Author: greenkeeper[bot]

package.json

@@ -97,7 +97,7 @@
     "ipfs-block-service": "~0.15.2",
     "ipfs-http-client": "^33.1.0",
     "ipfs-http-response": "~0.3.1",
-    "ipfs-mfs": "~0.11.6",
+    "ipfs-mfs": "~0.12.0",
     "ipfs-multipart": "~0.1.1",
     "ipfs-repo": "~0.26.6",
     "ipfs-unixfs": "~0.1.16",