New Updates for iOS Device Support file. Don't need to update Xcode.
You just need to add support file to Xcode's DeviceSupport folder.
iOS 12.3.1 Developer Disk Image
Extract the zip and then copy folder.
Paste this folder in this path
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport
Quit the Xcode and restart, it will work.