textproc/py-qrcode: Update to 7.4

Changes since 7.3:

• Improvements for embedded image.
• Restructure the factory drawers, allowing different shapes in SVG image factories as well.
• Add a `--factory-drawer option to the qr` console script.
• Optimize the output for the `SVGPathImage` factory (more than 30% reduction in file sizes).
• Add a `pypng image factory as a pure Python PNG solution. If pillow` is *not* installed, then this becomes the default factory.
• The `pymaging` image factory has been removed, but its factory shortcut and the actual PymagingImage factory class now just link to the PyPNGImage factory.

Reported by: portscout