Ancient RPi Imager screenshots

[lurch]

Whilst casting my eagle-eye over #771 I noticed that https://github.com/raspberrypi/rpi-imager/blob/qml/src/linux/rpi-imager.metainfo.xml.in has a bunch of image URLs, and I checked that they still existed at the new URL:

http://downloads.raspberrypi.com/imager/IMAGING-UTILITY-MAIN.png
http://downloads.raspberrypi.com/imager/IMAGING-UTILITY-OS.png
http://downloads.raspberrypi.com/imager/IMAGING-UTILITY-SD.png
http://downloads.raspberrypi.com/imager/IMAGING-UTILITY-WRITE.png
http://downloads.raspberrypi.com/imager/IMAGING-UTILITY-DONE.png

The good news is that the images do still exist at that new URL, but unfortunately they're super old! They all say "v1.2" in the title-bar, and some of them refer to the old "Raspbian" OS name, which is now called "Raspberry Pi OS".
Probably worth updating them at some point...