Update peerDependency to support pug@3

pugjs#126

Author: phacks

package.json

@@ -12,7 +12,7 @@
     "resolve": "^1.1.7"
   },
   "peerDependencies": {
-    "pug": "^2.0.0"
+    "pug": ">=2.0.0"
   },
   "devDependencies": {
     "mocha": "*",
@@ -27,4 +27,4 @@
     "url": "git://github.com/pugjs/pug-loader.git"
   },
   "license": "MIT"
-}
+}