fix build failure for aptos-core

[gedigi]

This PR asets the rust nightly version to generic to solve a build issue.

[github-actions]

gedigi is either the primary contact or is in the CCs list of projects/aptos-core.
gedigi has previously contributed to projects/aptos-core. The previous PR was #10904

[jonathanmetzman]

I think the failure is spurious right?

[gedigi]

I think the failure is spurious right?

Yes

[jonathanmetzman]

I think this won't work. Let me figure out an alternative.

[gedigi]

@jonathanmetzman we are changing approach a bit and this account is not going to be used - at least for now. however, this PR contains a fix for an existing build failure, so it would be awesome if you could merge it. thanks!

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@jonathanmetzman can this be approved please? we've been dealing with a build failure: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=62877

[gedigi]

gentle reminder. this PR is waiting to be merged for several weeks. how can we get it approved? thank you.