ci: fix new compile warn and clippy of 1.84

[dj8yfo]

looks like this was a new lint from rust-lang/rust#48919 ,
and the lint was correct about fs2::FileExt vs

    #[unstable(feature = "file_lock", issue = "130994")]
    pub fn unlock(&self) -> io::Result<()> {
        self.inner.unlock()
    }

[akorchyn]

@race-of-sloths score 5

[race-of-sloths]

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Current status: executed

Reviewer	Score
@akorchyn	5

Your contribution is much appreciated with a final score of 5!
You have received 58 (50 base + 15% lifetime bonus) Sloth points for this contribution

@akorchyn received 25 Sloth Points for reviewing and scoring this pull request.

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