Bump nock to resolve Node.js v22 deprecation

[harishkotra]

Summary

• bump nock in @polkadot/rpc-provider to a version that no longer triggers the Node.js v22 url.parse() deprecation warning
• refresh the lockfile to pick up the updated dependency tree
• re-enable the native-fetch HTTP provider test now that the mocked request path passes again

Testing

• yarn test:one packages/rpc-provider/src/http/index.spec.ts
• yarn test:one packages/rpc-provider/src/http/send.spec.ts

Fixes #6252