fix(deps): bump tonlibjson-sys/ton-testnet from 7262a66 to 51d5113

Bumps [tonlibjson-sys/ton-testnet](https://github.com/ton-blockchain/ton) from `7262a66` to `51d5113`.
- [Release notes](https://github.com/ton-blockchain/ton/releases)
- [Commits](ton-blockchain/ton@7262a66...51d5113)

---
updated-dependencies:
- dependency-name: tonlibjson-sys/ton-testnet
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>