Adding --json to lint

src/reuse/lint.py

@@ -252,12 +252,24 @@ def custom_serializer(obj):
             f"Object of type {obj.__class__.__name__} is not JSON serializable"
         )
 
+    def custom_sort_key(key):
+        order = {
+            "lint_version": 0,
+            "reuse_spec_version": 1,
+            "reuse_tool_version": 2,
+        }
+        return (order.get(key, 3), key)
+
+    report_dict = report.to_dict_lint()
+    sorted_report_dict = dict(
+        sorted(report_dict.items(), key=lambda item: custom_sort_key(item[0]))
+    )
+
     return json.dumps(
-        report.to_dict_lint(),
+        sorted_report_dict,
         indent=2,
         # Serialize sets to lists
         default=custom_serializer,
-        sort_keys=True,
     )