fix: migrate legacy upstream metadata (SPEC-M03)

dappnode_package.json

@@ -1,7 +1,13 @@
 {
   "name": "kovan.dnp.dappnode.eth",
   "version": "0.1.8",
-  "upstreamVersion": "2.6.4",
+  "upstream": [
+    {
+      "repo": "paritytech/parity-ethereum",
+      "version": "v2.6.4",
+      "arg": "PARITY_VERSION"
+    }
+  ],
   "shortDescription": "Ethereum testnet with Parity's PoA Protocol",
   "description": "Kovan is an Ethereum testnet using Parity's Proof of Authority consensus engine, with benefits over Ropsten: \n\n - Immune to spam attacks (as Ether supply is controlled by trusted parties) \n - Consistent 4 second block time \n\n\n For Parity support, head to the [Parity Gitter channel](https://gitter.im/ethcore/parity). After configuring, you probably want to acquire some Kovan Ether. To do so, follow the [faucet guide](https://github.com/kovan-testnet/faucet).",
   "type": "library",

docker-compose.yml

@@ -2,7 +2,10 @@ version: "3.4"
 services:
   kovan.dnp.dappnode.eth:
     image: "kovan.dnp.dappnode.eth:0.1.8"
-    build: .
+    build:
+      context: .
+      args:
+        PARITY_VERSION: v2.6.4
     volumes:
       - "kovan:/root/.local/share/io.parity.ethereum/"
     environment: