HPCC-27420 platform-core-debug is missing apt-get update

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

dockerfiles/platform-core-debug/Dockerfile

@@ -22,6 +22,7 @@ ARG DOCKER_REPO
 FROM ${DOCKER_REPO}/platform-build:${BUILD_LABEL}
 
 # Set the locale
+RUN apt-get update -y
 RUN apt-get install -y locales
 RUN locale-gen en_US.UTF-8
 ENV LANG en_US.UTF-8