Fix cloning attribute with namespace disappearing namespace

Closes GH-12547.

Fix GH-12532: PharData created from zip has incorrect timestamp

The datetime stored in the DOS time fields, which is what zip standard
uses, is local time without a timezone. There's an

Fix GH-12532: PharData created from zip has incorrect timestamp

The datetime stored in the DOS time fields, which is what zip standard
uses, is local time without a timezone. There's an extension to the zip
file format since '97 that allows storing a unix timestamp (in UTC) in
the header for both the central directory and the local entries.
This patch adds support for this.

Closes GH-12548.

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