SwifterPM 0.8.12 fixes __MACOSX artifact shadows and stalled resolve output

The SwifterPM dependency has been updated to 0.8.12, fixing two user-visible issues. Finder-zipped binary artifacts with a __MACOSX shadow bundle, such as Plaid’s LinkKit, no longer cause tuist generate to fail because the shadow copy is stripped and skipped. Also, tuist install now streams stdout and stderr from delegated swift package resolve runs so progress is visible instead of appearing stalled.