update demo to dev

[usama9500]

A brief description of the changes in this PR:
Updated the link from block_worker: https://demo.zus.network/dns to https://dev.zus.network/dns

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• blobber:
• gosdk:
• system_test:
• zboxcli:
• 0chain:
• Other: ...