Update Rust dependencie Cargo.toml

[ftieben]

add rdkafka-sys = "=1.2.2" as dependencie cause newer versions dont provide primitive_to_rd_kafka_resp_err_t

fede1024/rust-rdkafka#211

Description

What behavior does this PR change, and why?
per default, cargo installs a new version of rdkafka-sys which is not compatible with the installed rdkafka version anymore

Author Validation

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Reviewer Tasks

Describe the tasks/validation that the PR submitter is requesting to be done by the reviewer.
build the rust example

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