add missing import

Author: xinsong-cui

aws-runtime/aws-config/native/src/aws/sdk/kotlin/runtime/region/DefaultRegionProviderChainNative.kt

@@ -7,6 +7,7 @@ package aws.sdk.kotlin.runtime.region
 
 import aws.sdk.kotlin.runtime.config.imds.InstanceMetadataProvider
 import aws.sdk.kotlin.runtime.config.profile.AwsProfile
+import aws.smithy.kotlin.runtime.client.region.RegionProvider
 import aws.smithy.kotlin.runtime.io.Closeable
 import aws.smithy.kotlin.runtime.util.LazyAsyncValue
 import aws.smithy.kotlin.runtime.util.PlatformProvider