Use ValueTask.

This optimises the Open() sync codepath.

Author: bgrainger

src/MySqlConnector/Core/ConnectionPool.cs

@@ -17,7 +17,7 @@ internal sealed class ConnectionPool
 
 		public ConnectionSettings ConnectionSettings { get; }
 
-		public async Task<ServerSession> GetSessionAsync(MySqlConnection connection, IOBehavior ioBehavior, CancellationToken cancellationToken)
+		public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection, IOBehavior ioBehavior, CancellationToken cancellationToken)
 		{
 			cancellationToken.ThrowIfCancellationRequested();
 

src/MySqlConnector/MySql.Data.MySqlClient/MySqlConnection.cs

@@ -371,7 +371,7 @@ internal void FinishQuerying()
 			m_activeReader = null;
 		}
 
-		private async Task<ServerSession> CreateSessionAsync(IOBehavior? ioBehavior, CancellationToken cancellationToken)
+		private async ValueTask<ServerSession> CreateSessionAsync(IOBehavior? ioBehavior, CancellationToken cancellationToken)
 		{
 			var pool = ConnectionPool.GetPool(m_connectionString);
 			m_connectionSettings = pool?.ConnectionSettings ?? new ConnectionSettings(new MySqlConnectionStringBuilder(m_connectionString));