chore: update to ipld-dag-cbor 0.13

No further changes are needed as js-ipfs-api is getting the raw blocks
from IPFS and does the whole parsing client-sided in JavaScript.

BREAKING CHANGE: dag-cbor nodes now represent links as CID objects

The API for [dag-cbor](https://github.com/ipld/js-ipld-dag-cbor) changed.
Links are no longer represented as JSON objects (`{"/": "base-encoded-cid"}`,
but as [CID objects](https://github.com/ipld/js-cid). `ipfs.dag.get()` and
now always return links as CID objects. `ipfs.dag.put()` also expects links
to be represented as CID objects. The old-style JSON objects representation
is still supported, but deprecated.

Prior to this change:

```js
const cid = new CID('QmXed8RihWcWFXRRmfSRG9yFjEbXNxu1bDwgCFAN8Dxcq5')
// Link as JSON object representation
const putCid = await ipfs.dag.put({link: {'/': cid.toBaseEncodedString()}})
const result = await ipfs.dag.get(putCid)
console.log(result.value)

```

Output:

```js
{ link:
   { '/':
      <Buffer 12 20 8a…> } }
```

Now:

```js
const cid = new CID('QmXed8RihWcWFXRRmfSRG9yFjEbXNxu1bDwgCFAN8Dxcq5')
// Link as CID object
const putCid = await ipfs.dag.put({link: cid})
const result = await ipfs.dag.get(putCid)
console.log(result.value)
```

Output:

```js
{ link:
   CID {
     codec: 'dag-pb',
     version: 0,
     multihash:
      <Buffer 12 20 8a…> } }
```

See ipld/ipld#44 for more information on why this
change was made.

Author: vmx

package.json

@@ -38,7 +38,7 @@
     "glob": "^7.1.2",
     "ipfs-block": "~0.7.1",
     "ipfs-unixfs": "~0.1.15",
-    "ipld-dag-cbor": "~0.12.1",
+    "ipld-dag-cbor": "~0.13.0",
     "ipld-dag-pb": "~0.14.6",
     "is-ipfs": "~0.4.2",
     "is-pull-stream": "0.0.0",
@@ -82,7 +82,7 @@
     "eslint-plugin-react": "^7.10.0",
     "go-ipfs-dep": "~0.4.17",
     "gulp": "^3.9.1",
-    "interface-ipfs-core": "~0.80.0",
+    "interface-ipfs-core": "~0.81.0",
     "ipfsd-ctl": "~0.39.0",
     "pull-stream": "^3.6.8",
     "socket.io": "^2.1.1",