Recognize pascal-case identifiers that ends with 2 or more upper case letters as pascal_case_class (#908)

Co-authored-by: Seth <seth_lyu@aoki7studio.com>

syntaxes/GDScript.tmLanguage.json

@@ -454,7 +454,7 @@
 			"name": "variable.other.constant.gdscript"
 		},
 		"pascal_case_class": {
-			"match": "\\b([A-Z]+[a-z_0-9]*([A-Z]?[a-z_0-9]+)*[A-Z]?)\\b",
+			"match": "\\b[A-Z]+(?:[a-z]+[A-Za-z0-9_]*)+\\b",
 			"name": "entity.name.type.class.gdscript"
 		},
 		"signal_declaration_bare": {