Make KRR allocate `@safe`

[denisa1208]

My PR revives the original PR (https://github.com/dlang/phobos/actions/runs/12297111982/job/34317628480?pr=10585)

[dlang-bot]

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Testing this PR locally

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dub run digger -- build "master + phobos#10585"

[0xEAB]

Reference: https://github.com/dlang/phobos/pull/6416

[LightBender]

This PR has had a broken CI for 6+ months, please reopen if you plan to continue working on this.