fix: correctly recognize multiple inheritance for @class

Problem: Inheritance from multiple parent types are not correctly
recognized, only the first parent class was parsed as identifier.

Solution: Use commaSep to recognize multiple parent types.

grammar.js

@@ -49,7 +49,7 @@ module.exports = grammar({
     class_annotation: $ => seq(
       '@class',
       $.type,
-      optional(seq(':', $.type)),
+      optional(seq(':', commaSep1($.type))),
       optional(choice($.class_at_comment, $.comment)),
     ),
 

src/grammar.json

@@ -124,8 +124,29 @@
                   "value": ":"
                 },
                 {
-                  "type": "SYMBOL",
-                  "name": "type"
+                  "type": "SEQ",
+                  "members": [
+                    {
+                      "type": "SYMBOL",
+                      "name": "type"
+                    },
+                    {
+                      "type": "REPEAT",
+                      "content": {
+                        "type": "SEQ",
+                        "members": [
+                          {
+                            "type": "STRING",
+                            "value": ","
+                          },
+                          {
+                            "type": "SYMBOL",
+                            "name": "type"
+                          }
+                        ]
+                      }
+                    }
+                  ]
                 }
               ]
             },