permission: fix recent coverity warning

[mhdawson]

• address recent coverity warning by using auto &. Since the value is already const using a copy should not be necessary.

[nodejs-github-bot]

Review requested:

• @nodejs/security-wg

[mhdawson]

This is the reported coverity warning:

   if (node->children.size()) {
 93      int child = 0;
   	
CID 322084 (#1 of 1): AUTO_CAUSES_COPY (AUTO_CAUSES_COPY)
1. auto_causes_copy: Using the auto keyword without an & causes the copy of an object of type pair.
   	Use auto & instead of auto.
 94      for (const auto pair : node->children) {

Since pair is const, it seems to make sense to avoid a copy byusing auto &

[RafaelGSS]

See: #48770

[mhdawson]

ok see its been covered.