audit security vulnerabilities as part of ci (#280)

package.json

@@ -27,6 +27,7 @@
     "directory": "packages/exec"
   },
   "scripts": {
+    "audit-moderate": "npm install && npm audit --audit-level=moderate",
     "test": "echo \"Error: run tests from root\" && exit 1",
     "tsc": "tsc"
   },