ci: Pull the Zephyr CI docker image from GitHub container reg.

This image is 15GB so in theory this may be faster, although
in testing the improvement is either non-existent or marginal.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <[email protected]>

Author: projectgus

tools/ci.sh

@@ -747,7 +747,7 @@ ZEPHYR_SDK_VERSION=0.16.8
 ZEPHYR_VERSION=v3.7.0
 
 function ci_zephyr_setup {
-    IMAGE=zephyrprojectrtos/ci:${ZEPHYR_DOCKER_VERSION}
+    IMAGE=ghcr.io/zephyrproject-rtos/ci:${ZEPHYR_DOCKER_VERSION}
 
     docker pull ${IMAGE}