Update futures-util crate in Secrets SDK

[t1m0thyj]

What It Does

Updates the futures-util crate since all versions prior to v0.3.31 were yanked.

How to Test

Review Checklist
I certify that I have:

• tested my changes
• added/updated automated tests
• updated the changelog
• followed the contribution guidelines

Additional Comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.07%. Comparing base (64bc3ca) to head (f79a68e).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #337   +/-   ##
=======================================
  Coverage   89.07%   89.07%           
=======================================
  Files          65       65           
  Lines        3249     3249           
=======================================
  Hits         2894     2894           
  Misses        355      355           

Flag	Coverage Δ
unittests	89.07% <ø> (ø)

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