Update unified-engine

Author: wooorm

package.json

@@ -28,7 +28,7 @@
     "json5": "^1.0.0",
     "minimist": "^1.2.0",
     "text-table": "^0.2.0",
-    "unified-engine": "^5.1.0"
+    "unified-engine": "^6.0.0"
   },
   "devDependencies": {
     "bail": "^1.0.0",
@@ -40,7 +40,7 @@
     "strip-ansi": "^4.0.0",
     "tape": "^4.4.0",
     "touch": "^3.0.0",
-    "unified": "^6.0.0",
+    "unified": "^7.0.0",
     "vfile-reporter-json": "^1.0.1",
     "xo": "^0.21.0",
     "xtend": "^4.0.1"