Add ISO format to backup file matcher

app/src/main/java/org/tasks/backup/BackupConstants.kt

@@ -10,7 +10,7 @@ object BackupConstants {
     const val EXPORT_FILE_NAME = "user.%s.json"
     const val BACKUP_FILE_NAME = "auto.%s.json"
 
-    private val MATCHER = Pattern.compile("""(auto|user)\.(\d{2})(\d{2})(\d{2})-(\d{2})(\d{2})\.json""")
+    private val MATCHER = Pattern.compile("""(auto|user)\.(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})\.json""")
 
     fun isBackupFile(name: String?) = name?.let { MATCHER.matcher(it).matches() } ?: false
 
@@ -32,7 +32,7 @@ object BackupConstants {
                 .takeIf { it.matches() }
                 ?.let {
                     DateTime(
-                            2000 + it.group(2)!!.toInt(),
+                            it.group(2)!!.toInt(),
                             it.group(3)!!.toInt(),
                             it.group(4)!!.toInt(),
                             it.group(5)!!.toInt(),