[#327] Fix backup screen crash

This was a minor regression, as the string formatter was using %d for a number while the calculateBirthday method was returning a BlockHeight object

app/src/main/java/cash/z/ecc/android/ui/setup/BackupFragment.kt

@@ -88,7 +88,7 @@ class BackupFragment : BaseFragment<FragmentBackupBinding>() {
     override fun onResume() {
         super.onResume()
         resumedScope.launch {
-            binding.textBirtdate.text = getString(R.string.backup_format_birthday_height, calculateBirthday())
+            binding.textBirtdate.text = getString(R.string.backup_format_birthday_height, calculateBirthday().value)
         }
     }