.circleci/config.yml: use uroottest/test-image-amd64:latest
.circleci/config.yml: use uroottest/test-image-amd64:latest

This PR updates .circleci/config.yml to use
uroottest/test-image-amd64:latest which uses QEMU v4.2.0

Signed-off-by: Tim Rots <303d85e35fdeaa7baaeca9350aad42402c9e3308@protonmail.ch>

u-root/u-root,u-root/u-root,hugelgupf/u-root,u-root/u-root,hugelgupf/u-root,hugelgupf/u-root,hugelgupf/u-root