I am running a modified asset_tracker_v2 on a nRF9160. all is working fine. I am upgrading from SDK v2.5 to SDK 2.90. After a build I find the merged.hex file under the build directory. It used to be under build/zephyr. I can not find the app_update.bin that is needed for FOTA operation. Can you tell me what bin file I use for FOTA operations with SDK 2.9.0. I would appreciate any help you can give. The FOTA operation is essential since our customers are spread over many locations and we cannot update each location locally.