github: workflows: Update other docker image reference

The twister workflow contains two references to the docker image to use.
The earlier change only updated one of these.  Update the other to
match.  This should allow rust code to be built in the whole twister
workflow.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

.github/workflows/twister.yaml

@@ -129,7 +129,7 @@ jobs:
     needs: twister-build-prep
     if: needs.twister-build-prep.outputs.size != 0
     container:
-      image: ghcr.io/zephyrproject-rtos/ci-repo-cache:v0.26.13.20240601
+      image: ghcr.io/zephyrproject-rtos/ci-repo-cache:v0.26.14.20240823
       options: '--entrypoint /bin/bash'
     strategy:
       fail-fast: false