Update deepmerge

Author: wooorm

package.json

@@ -24,7 +24,7 @@
   },
   "devDependencies": {
     "browserify": "^13.0.1",
-    "deepmerge": "^0.2.10",
+    "deepmerge": "^1.2.0",
     "esmangle": "^1.0.1",
     "hast-util-to-html": "^2.1.0",
     "hastscript": "^3.0.0",