Fix min amount for collateral return

[cffls]

This commit fixes errors "Minimum lovelace amount for collateral return x is greater than collateral change y". The root cause is that the collateral return can contain multi-assets that might exceed the minimum ADA required to hold them.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.68%. Comparing base (6c2d183) to head (5b42b60).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #403      +/-   ##
==========================================
- Coverage   85.74%   85.68%   -0.07%     
==========================================
  Files          32       32              
  Lines        4202     4204       +2     
  Branches     1052     1052              
==========================================
- Hits         3603     3602       -1     
- Misses        422      423       +1     
- Partials      177      179       +2     

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