CI: install telnet into the images

runfvp currently needs telnet to communicate with the guest, so install
telnet into the image.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -27,6 +27,7 @@ stages:
     - mkdir --verbose --parents $KAS_WORK_DIR $KAS_REPO_REF_DIR $SSTATE_DIR $DL_DIR $TOOLCHAIN_DIR $TOOLCHAIN_LINK_DIR
     # Must do this here, as it's the only way to make sure the toolchain is installed on the same builder
     - ./ci/get-binary-toolchains $DL_DIR $TOOLCHAIN_DIR $TOOLCHAIN_LINK_DIR
+    - sudo apt update && sudo apt install telnet -y
 
 # Generalised fragment to do a Kas build
 .build: