[meta] run aud in posttest

Author: ljharb

Diff for: package.json

@@ -41,6 +41,7 @@
         "through": "^2.3.8"
     },
     "devDependencies": {
+        "aud": "^1.1.3",
         "concat-stream": "^1.6.2",
         "eclint": "^2.8.1",
         "ecstatic": "^4.1.4",
@@ -55,6 +56,7 @@
         "lint": "eslint . bin/*",
         "pretest": "npm run lint",
         "test": "npm run tests-only",
+        "posttest": "aud --production",
         "tests-only": "nyc tap test/*.js"
     },
     "testling": {