nova-fairwinds: update checksum for 3.12.0 release

[stefanb]

Release workflow history in circleci https://app.circleci.com/pipelines/github/FairwindsOps/nova
indicates that 2 release jobs were run in circle ci:

• first, failed https://app.circleci.com/pipelines/github/FairwindsOps/nova/986 on commit FairwindsOps/nova@dc7abe9 by @vitorvezani:
  

• second, successful https://app.circleci.com/pipelines/github/FairwindsOps/nova/989 on commit FairwindsOps/nova@0803b08 also by @vitorvezani:
  

Diff: FairwindsOps/nova@dc7abe9...0803b08
contains just circleci config change.

Ref:

• https://github.com/FairwindsOps/nova/releases/tag/v3.12.0
• nova-fairwinds 3.12.0 #279692
• go 1.27.0, go@1.26 1.26.7 (new formula) #288803

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• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>?
• Is your test running fine brew test <formula>?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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