build(deps): bump soroban-sdk from 23.5.0 to 27.0.6 in /contract

Bumps [soroban-sdk](https://github.com/stellar/rs-soroban-sdk) from 23.5.0 to 27.0.6.
- [Commits](stellar/rs-soroban-sdk@v23.5.0...v27.0.6)

---
updated-dependencies:
- dependency-name: soroban-sdk
  dependency-version: 27.0.6
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]