Add usize cast to clippy::manual_bits suggestion

[xFrednet]

A fix for the suggestion from #8213

changelog: [manual_bits]: The suggestion now includes a cast for proper type conversion

[rust-highfive]

r? @giraffate

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[giraffate]

The test fails in ui/manual_bits.rs, can this be updated?

[xFrednet]

Thank you for the message, I've missed the failed CI. Now it should be ready, the update only added clippy::useless_conversion to the allowed lint list in the test file :)

[giraffate]

Can the example in doc be updated like below?

    /// ### Example
    /// ```rust
    /// std::mem::size_of::<usize>() * 8;
    /// ```
    /// Use instead:
    /// ```rust
    /// usize::BITS as usize;
    /// ```

[giraffate]

@bors r+

Thanks!

[bors]

📌 Commit 3bd0ac7 has been approved by giraffate

[bors]

⌛ Testing commit 3bd0ac7 with merge ecb3c3f...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: giraffate
Pushing ecb3c3f to master...