Temporarily ignore rustsec warning for unmaintained instant

[clux]

Via #1635
Should ideally upgrade out the library or find a replacement, but it's not super serious. Making builds green for now.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.3%. Comparing base (9c402a6) to head (18bcc9a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1636   +/-   ##
=====================================
  Coverage   75.3%   75.3%           
=====================================
  Files         82      82           
  Lines       7348    7348           
=====================================
  Hits        5528    5528           
  Misses      1820    1820           

[nightkr]

This should be fine, instant is a pretty trivial crate (especially if you don't care about wasm). It does mean it will trigger the same warning for downstream users though.