Duplicate Header Values are Lost #17
Description
The Fetch.Internal.Headers.toHeaders function uses fromFoldable which discards duplicate header names.
I suggest replacing fromFoldable with fromFoldableWith in Fetch.Internal.Headers.toHeaders to preserve all header values, addressing the loss of duplicate header values in the response.
toHeaders :: CoreHeaders.Headers -> Map.Map CaseInsensitiveString String
toHeaders = CoreHeaders.toArray >>> map (lmap CaseInsensitiveString) >>> Map.fromFoldable