iox-#70 Fix clippy warnings

[elBoberido]

Pre-Review Checklist for the PR Author

1. [x] Code follows the Rust coding style and is formatted with rustfmt
2. [x] Branch follows the naming format (iox-123-this-is-a-branch)
3. [x] Commits messages are according to this guideline
   • [x] Commit messages have the issue ID (iox-#42 commit text)
   • [x] Commit author matches Eclipse Contributor Agreement (and ECA is signed)
4. [x] Update the PR title
   • Follow the same conventions as for commit messages
   • Link to the relevant issue
5. [x] Relevant issues are linked
6. [x] Add sensible notes for the reviewer
7. [x] All checks have passed (except task-list-completed)
8. [x] Assign PR to reviewer

Notes for Reviewer

This PR fixes all the clippy warnings.

Checklist for the PR Reviewer

• [ ] Commits are properly organized and messages are according to the guideline
• [ ] Code according to our coding style and naming conventions
• [ ] PR title describes the changes

Post-review Checklist for the PR Author

1. [ ] All open points are addressed and tracked via issues

References

• Closes #70

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 35.24590% with 79 lines in your changes missing coverage. Please review.

Project coverage is 49.83%. Comparing base (f7573d8) to head (55d6aee).

Files with missing lines	Patch %	Lines
iceoryx-sys/src/introspection/port.rs	0.00%	26 Missing :warning:
iceoryx-sys/src/introspection/process.rs	0.00%	15 Missing :warning:
iceoryx-sys/src/subscriber.rs	59.45%	15 Missing :warning:
iceoryx-sys/src/introspection/memory.rs	0.00%	12 Missing :warning:
iceoryx-sys/src/publisher.rs	57.69%	11 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #71 +/- ## ========================================== - Coverage 50.77% 49.83% -0.95% ========================================== Files 20 20 Lines 1154 1202 +48 ========================================== + Hits 586 599 +13 - Misses 568 603 +35 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.