[SDK] Fix stray keccak256 reference (#7089)

## Summary
- remove unused `keccak256` import
- clean up unused statement in `resolve-l2-name`

## Testing
- `pnpm test` *(fails: EHOSTUNREACH)*

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## PR-Codex overview
This PR focuses on removing an unused import of the `keccak256` function from the `resolve-l2-name.ts` file, which helps in cleaning up the code and improving readability.

### Detailed summary
- Removed the import statement for `keccak256` from `viem` in `packages/thirdweb/src/extensions/ens/resolve-l2-name.ts`.

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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **Chores**
  - Removed unused code and imports to improve code cleanliness.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: joaquim-verges

packages/thirdweb/src/extensions/ens/resolve-l2-name.ts

@@ -4,7 +4,6 @@ import * as ox__Bytes from "ox/Bytes";
 import * as ox__Ens from "ox/Ens";
 import * as ox__Hash from "ox/Hash";
 import * as ox__Hex from "ox/Hex";
-import { keccak256 } from "viem";
 import type { Chain } from "../../chains/types.js";
 import type { ThirdwebClient } from "../../client/client.js";
 import { getContract } from "../../contract/contract.js";
@@ -47,7 +46,6 @@ const convertReverseNodeToBytes = (address: Address, chainId: number) => {
       [reverseNode, addressNode],
     ),
   );
-  keccak256;
   return addressReverseNode;
 };