remove const hack in alloc

[Syvraa]

Seems like this change was missed when other const hacks were removed.

[rustbot]

Thanks for the pull request, and welcome! The Rust Project is excited to review your changes, and you should hear from @LawnGnome (or someone else) some time within the next two weeks.

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[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rust-log-analyzer]

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[Syvraa]

huh, weird