fix: coin98 wallet add signMessage method

[khiemsoft]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Type of change.

• FIX - a PR of this type patches a bug.
• FEATURE - a PR of this type introduces a new feature.
• BUILD - a PR of this type introduces build changes.
• CI - a PR of this type introduces CI changes.
• DOCS - a PR of this type introduces DOCS improvement.
• STYLE - a PR of this type introduces style changes.
• REFACTOR - a PR of this type introduces refactoring.
• PERFORMANCE - a PR of this type introduces performance changes.
• TEST - a PR of this type adds more tests.
• CHORE - a PR introduces other changes than the specified above.

[trechriron]

Please make a template selection above, fill in the details, and mark the appropriate checkboxes. Thanks!

[trechriron]

1. Please find and copy the correct template for your initial comment. You may have to resubmit. Please close this one if you do. You MUST have the checkboxes present or tests will not pass.
2. Always make your initial PR against the DEV branch.

After these are fixed, we can review your changes. Thanks!

[trechriron]

@khiemsoft - did you see my request for changes?

[khiemsoft]

@khiemsoft - did you see my request for changes?

Hi, I just fixed this warning. Please verify it. Thanks for your support.