cad/py-gdspy: update 1.6.11 => 1.6.13

Changelog:

Version 1.6.13 (Apr 26, 2023)
  Allow ill-formed GDSII label anchors to be correctly loaded.
Version 1.6.12 (Jun 2, 2022)
  Fix in Cell.get_texttypes.
  Allow labels to inherit transforms through get_labels.

https://github.com/heitzmann/gdspy/blob/v1.6.13/README.md#version-1613-apr-26-2023

• Replace PORTVERSION with DISTVERSION
• Move plist entries to dedicated pkg-plist
• Small linting and sorting entries to portclippy(1)

PR: 285508
Approved by: hrs (maintainer, timeout > 2 months)