Add scriv changelog fragment for MultiAssetReturnCollateral fix

Author: Jimbo4350

cardano-testnet/changelog.d/20260331_140000_jordan_fix_flaky_multiasset_collateral.md

@@ -0,0 +1,60 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Removed
+
+- A bullet item for the Removed category.
+
+-->
+<!--
+### Added
+
+- A bullet item for the Added category.
+
+-->
+<!--
+### Changed
+
+- A bullet item for the Changed category.
+
+-->
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category.
+
+-->
+### Fixed
+
+- Fixed flaky `MultiAssetReturnCollateral` test by using deterministic UTxO
+  selection instead of relying on query ordering.
+
+<!--
+### Security
+
+- A bullet item for the Security category.
+
+-->
+<!--
+### Tests
+
+- A bullet item for the Tests category.
+
+-->
+<!--
+### Documentation
+
+- A bullet item for the Documentation category.
+
+-->
+<!--
+### Maintenance
+
+- A bullet item for the Maintenance category.
+
+-->