fix(rust-server): remove redundant clone

[nathanielc]

The generated example code would clone the context. However as context is a generic type and is not declared to implement Clone, a clone of a reference is just a copy of the reference and therefore unnecessary. This change removes the redundant call and therefore avoids the cargo clippy warning.

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@jacob-pro

[wing328]

cc @frol (2017/07) @farcaller (2017/08) @richardwhiuk (2019/07) @paladinzh (2020/05) @jacob-pro (2022/10)

[wing328]

thanks for the PR, which has been merged.