Replace deprecated native StringBuilder.deleteCharAt

Author: ilya-g

core/nativeMain/src/Instant.kt

@@ -171,8 +171,8 @@ public actual class Instant internal constructor(actual val epochSeconds: Long,
             if (hi < 0) {
                 when {
                     ldt.year == -10000 -> {
-                        buf.deleteCharAt(pos)
-                        buf.deleteCharAt(pos)
+                        buf.deleteAt(pos)
+                        buf.deleteAt(pos)
                         buf.insert(pos, (hi - 1).toString())
                     }
                     lo == 0L -> {

core/nativeMain/src/LocalDate.kt

@@ -224,9 +224,9 @@ public actual class LocalDate actual constructor(actual val year: Int, actual va
         val buf = StringBuilder(10)
         if (absYear < 1000) {
             if (yearValue < 0) {
-                buf.append(yearValue - 10000).deleteCharAt(1)
+                buf.append(yearValue - 10000).deleteAt(1)
             } else {
-                buf.append(yearValue + 10000).deleteCharAt(0)
+                buf.append(yearValue + 10000).deleteAt(0)
             }
         } else {
             if (yearValue > 9999) {