Removed warnings

[sdoerig]

Description

Removed Rust 1.53.0 compiler warnigs.

Author Validation

Writing messages still works

Reviewer Tasks

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

[sdoerig]

Fixed all the compiler warnings when compiling with Rust 1.53.0

[ybyzek]

@frankgreco would you be available to review this PR?

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