fix: make apt-get update work all the time (#51)

Author: stasadev

web-build/Dockerfile.ddev-cron

@@ -1,6 +1,6 @@
 #ddev-generated
 # Install cron package; this can be done in webimage_extra_packages, but put it here for now.
-RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y -o Dpkg::Options::="--force-confold" --no-install-recommends --no-install-suggests cron
+RUN (apt-get update || true) && DEBIAN_FRONTEND=noninteractive apt-get install -y -o Dpkg::Options::="--force-confold" --no-install-recommends --no-install-suggests cron
 
 # Copy our custom config
 COPY ./cron.conf /etc/supervisor/conf.d/cron.conf