Fix default_connection when upgrade

CHANGELOG.rst

@@ -4,6 +4,9 @@ ChangeLog
 
 0.1
 ===
+0.1.9
+-----
+- Fix default_connection when upgrade
 
 0.1.8
 -----

aerich/migrate.py

@@ -174,7 +174,10 @@ class Migrate:
         temp_config = deepcopy(config)
         path = os.path.join(location, app, cls.old_models)
         path = path.replace("/", ".").lstrip(".")
-        temp_config["apps"][cls.diff_app] = {"models": [path]}
+        temp_config["apps"][cls.diff_app] = {
+            "models": [path],
+            "default_connection": config.get("apps").get(app).get("default_connection","default"),
+        }
         return temp_config
 
     @classmethod