Explicitly specify collation when resetting connection. Fixes #243

Since the 'collation_connection' system variable is only used for comparing string literals, it should be safe to always use utf8mb4_bin (for consistency) and not accept the server's current default collation for utf8mb4.

Author: bgrainger

src/MySqlConnector/Serialization/MySqlSession.cs

@@ -229,7 +229,7 @@ public async Task ResetConnectionAsync(ConnectionSettings cs, IOBehavior ioBehav
 				OkPayload.Create(payload);
 
 				// the "reset connection" packet also resets the connection charset, so we need to change that back to our default
-				payload = new PayloadData(new ArraySegment<byte>(PayloadUtilities.CreateEofStringPayload(CommandKind.Query, "SET NAMES utf8mb4;")));
+				payload = new PayloadData(new ArraySegment<byte>(PayloadUtilities.CreateEofStringPayload(CommandKind.Query, "SET NAMES utf8mb4 COLLATE utf8mb4_bin;")));
 				await SendAsync(payload, ioBehavior, cancellationToken).ConfigureAwait(false);
 				payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
 				OkPayload.Create(payload);