Update composer.json, fixing license for packagist

composer.json

@@ -3,7 +3,7 @@
 	"type": "typo3-cms-extension",
 	"description": "RTE integration of TinyMCE for TYPO3.",
 	"homepage": "https://www.sgalinski.de",
-	"license": "GPL-2.0+",
+	"license": "GPL-2.0-or-later",
 	"version": "3.0.2",
 	"support": {
 		"issues": "https://gitlab.sgalinski.de/typo3/tinymce4_rte/issues"