build: clippy disallow futures::pin_mut macro

[koivunej]

std has had pin! macro for some time, there is no need for us to use the older alternatives. Cannot disallow tokio::pin because tokio macros use that for msrv reasons (didn't check).

[github-actions]

2484 tests run: 2361 passed, 0 failed, 123 skipped (full report)

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Code coverage* (full report)

• functions: 28.8% (6959 of 24199 functions)
• lines: 47.2% (42610 of 90195 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
2c464b2 at 2024-03-05T10:28:18.523Z :recycle:}