Modify update-lastmod script to ignore advisories directory

Review Request #638 — Created May 4, 2021 and discarded — Latest diff uploaded

Information

pidgin/nest
default

Reviewers

If we do not do this then this script will end up changing the date for the
different markdown files corresponding to the CVEs and it'll mess up the
dates that each CVE was announced.
  1. Built docker image
  2. Verified update-lastmod.js did not update the advisories files and did not throw any extra errors
  3. Ran the docker image and verified dates got updated for all pages but the advisories ones