[AP-29] Fix duplicate JavaScript loading

[jbirdjavi]

...and security gem updates.

See https://jira.cru.org/browse/AP-29

The ActiveAdmin JS code was getting loaded twice, which was causing two form fields to be added with every click.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.27%. Comparing base (37082f1) to head (7f6a4f4).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #165   +/-   ##
=======================================
  Coverage   96.27%   96.27%           
=======================================
  Files          28       28           
  Lines         483      483           
=======================================
  Hits          465      465           
  Misses         18       18           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[stage-branch-merger]

I see you added the "On Staging" label, I'll get this merged to the staging branch!