Dockerfile: Use CI image v0.27.4 as base image

This commit updates the Dockerfile to use the CI image v0.27.4 as the
base image.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

Dockerfile

@@ -1,4 +1,4 @@
-FROM ghcr.io/zephyrproject-rtos/ci:v0.27.3
+FROM ghcr.io/zephyrproject-rtos/ci:v0.27.4
 
 # Cache Zephyr repositories
 RUN mkdir -p /repo-cache/zephyrproject && \