refactor: use maps.Copy for cleaner map handling

[russcoss]

There is a new function added in the go1.21 standard library, which can make the code more concise and easy to read.

[Copilot]

Pull Request Overview

This PR refactors the merge function to use Go 1.21's new maps.Copy function for cleaner and more idiomatic map copying operations.

• Imports the maps package from Go's standard library
• Replaces manual key-value iteration with maps.Copy function
• Renames function parameter to avoid naming conflict with imported package

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[russcoss]

@louisinger @tiero Hi, If there's anything need I to do, please feel free to let me know.