config: treat otps as strings to not eat leading zeros

Credit: @iarna

Author: iarna

lib/config/defaults.js

@@ -319,7 +319,7 @@ exports.types = {
   only: [null, 'dev', 'development', 'prod', 'production'],
   optional: Boolean,
   'package-lock': Boolean,
-  otp: Number,
+  otp: [null, String],
   'package-lock-only': Boolean,
   parseable: Boolean,
   'prefer-offline': Boolean,