Upgrade to Coroutines 1.5.0

This commit upgrades to Coroutines 1.5.0 while retaining
Coroutines 1.4.x compatibility.

Closes gh-26897

spring-messaging/src/main/kotlin/org/springframework/messaging/rsocket/RSocketRequesterExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -102,6 +102,7 @@ inline fun <reified T : Any> RSocketRequester.RequestSpec.dataWithType(flow: Flo
  * @author Sebastien Deleuze
  * @since 5.2
  */
+@Suppress("DEPRECATION")
 suspend fun RSocketRequester.RetrieveSpec.sendAndAwait() {
 	send().awaitSingleOrNull()
 }
@@ -121,6 +122,7 @@ suspend inline fun <reified T : Any> RSocketRequester.RetrieveSpec.retrieveAndAw
  * @author Sebastien Deleuze
  * @since 5.2.1
  */
+@Suppress("DEPRECATION")
 suspend inline fun <reified T : Any> RSocketRequester.RetrieveSpec.retrieveAndAwaitOrNull(): T? =
 		retrieveMono(object : ParameterizedTypeReference<T>() {}).awaitSingleOrNull()