Update schema to match generated schema

Signed-off-by: Gary O'Neall <gary@sourceauditor.com>

Author: goneall

resources/spdx-schema-v3.0.1.json

@@ -603,6 +603,16 @@
                                 }
                             ]
                         },
+                        "extension": {
+                            "anyOf": [
+                                {
+                                    "type": "array",
+                                    "items": {
+                                        "$ref": "#/$defs/prop_Element_extension"
+                                    }
+                                }
+                            ]
+                        },
                         "externalIdentifier": {
                             "anyOf": [
                                 {
@@ -658,6 +668,9 @@
         "prop_Element_extension": {
             "$ref": "#/$defs/extension_Extension_derived"
         },
+        "prop_Element_extension": {
+            "$ref": "#/$defs/extension_Extension_derived"
+        },
         "prop_Element_externalIdentifier": {
             "$ref": "#/$defs/ExternalIdentifier_derived"
         },