Use master branch for snapshot

[kazutoiris]

What is the purpose of the change

This PR updates the snapshot's source branch from dev-1.6.0 to master.

The main reason for this change is that the dev-1.6.0 branch no longer exists, and all current development activities are now based on the master branch.

Related issues/PRs

None.

Brief change log

• Change branch from dev-1.6.0 to master.

Checklist

• I have read the Contributing Guidelines on pull requests.
• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the Linkis mailing list first)
• If this is a code change: I have written unit tests to fully verify the new behavior.

[casionone]

LGTM.