chore(goimports): consolidate import names for "github.com/opencontainers/go-digest"

The following discussion from !818 (merged) should be addressed:

• @jaime started a discussion: (+1 comment)

  I'll revert this, but the package is already named digest so we don't need to label it here, I'll open a follow-up

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Doing a global search shows we have many instances of this import, and we have a mix of uses with/without labelling the import

Since the package name is digest this label is redundant so we should remove it