Add 'zepter' to CI workflow to detect faulty feature configuration

[ebma]

Context

There is a tool called zepter that can be used to analyze, fix and format features in Rust workspaces. We want to use this tool to detect faulty feature configurations sooner.

TODO

Add zepter to our GitHub CI actions to automatically check for faulty configurations. For reference see for example the definition here.

[ebma]

@pendulum-chain/product this is a nice-to-have feature that could probably help us identify some subtle bugs earlier.

[prayagd]

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