add Pico plugin API version 4

Signed-off-by: derMart <derMart@users.noreply.github.com>

Author: derMart

lib/Model/Plugin.php

@@ -46,6 +46,7 @@ class Plugin implements \JsonSerializable
 		Pico::API_VERSION_1,
 		Pico::API_VERSION_2,
 		Pico::API_VERSION_3,
+		Pico::API_VERSION_4,
 	];
 
 	/** @var MiscService */

lib/Pico.php

@@ -71,6 +71,13 @@ class Pico extends \Pico
 	 */
 	public const API_VERSION_3 = 3;
 
+	/**
+	 * API version 4, used by Pico 3.0
+	 *
+	 * @var int
+	 */
+	public const API_VERSION_4 = 4;
+
 	/** @var PicoService */
 	private $picoService;