The CVE doesn't impact us, so we can ignore it safely. This improves the
comment above the ignored entry in deny.toml. We test our own code via
`clippy` and we aren't using the vulnerable type. Our dependencies could
in theory use it, but that seems rather unlikely.
Testing: test-tidy is tested in CI.
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Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>
