Remove redundant @OptIn targeting new case conversion api

libraries/stdlib/js/src/kotlin/text/string.kt

@@ -240,7 +240,6 @@ public inline fun String.match(regex: String): Array<String>? = asDynamic().matc
 @kotlin.internal.InlineOnly
 internal inline fun String.nativeReplace(pattern: RegExp, replacement: String): String = asDynamic().replace(pattern, replacement)
 
-@OptIn(ExperimentalStdlibApi::class)
 @SinceKotlin("1.2")
 @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
 public actual fun String.compareTo(other: String, ignoreCase: Boolean = false): Int {