FEATURE: always update docker image for dev prior to launching

Previously people could stay stuck on old dev images, this ensures they
are always on latest when booting

bin/docker/boot_dev

@@ -64,6 +64,7 @@ mkdir -p "${DATA_DIR}"
 # 9292 unicorn
 # 9405 prometheus exporter
 
+docker pull discourse/discourse_dev:release
 docker run -d -p 9405:9405 -p 1080:1080 -p 3000:3000 -p 9292:9292 -v "$DATA_DIR:/shared/postgres_data:delegated" -v "$SOURCE_DIR:/src:delegated" $ENV_ARGS --hostname=discourse --name=discourse_dev --restart=always discourse/discourse_dev:release /sbin/boot
 
 if [ "${initialize}" = "initialize" ]; then