Add an srp for a cardano-ledger with the UTxO decoding fix

[neilmayhew]

Changelog

- description: |
    Hotfix for `cardano-cli-10.15.0.0` to fix a decoding error when querying the whole UTxO
  type:
  - bugfix         # fixes a defect

Context

The bug was reported by @CarlosLopezDeLara on 2026-03-03. It affects only queries, and only when querying the whole UTxO because of some historical TxOuts that are no longer relevant.

How to trust this PR

The only change is an srp (source-repository-package) stanza pointing to a branch in cardano-ledger that contains a couple of small fixes to decoding.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff