Remove cargo audit ignore for RUSTSEC-2021-0070

[ghost]

Describe the bug

In the cargo audit build step we are ignore RUSTSEC-2021-0070 because the statrs repository has not yet updated the nalgebra dependency to the latest version. Once they do, update the statrs dependency to resolve this issue.

To Reproduce
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Log output
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Expected behaviour
cargo audit should pass

Screenshots
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Environment (please complete the following information):
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Other information and links
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[q9f]

We no longer ignore this; merging with #1234.