fix: error when there is __init__.py in the migration folder (#272)

* fix: error when there is __init__.py in the migration folder

* fix: check __init__.py in the migration folder

* refactor

* refactor & add test

* refactor

* Update changelog

---------

Co-authored-by: Waket Zheng <waketzheng@gmail.com>

aerich/migrate.py

@@ -54,10 +54,18 @@ class Migrate:
 
     @classmethod
     def get_all_version_files(cls) -> List[str]:
-        return sorted(
-            filter(lambda x: x.endswith("py"), os.listdir(cls.migrate_location)),
-            key=lambda x: int(x.split("_")[0]),
-        )
+        def get_file_version(file_name: str) -> str:
+            return file_name.split("_")[0]
+
+        def is_version_file(file_name: str) -> bool:
+            if not file_name.endswith("py"):
+                return False
+            if "_" not in file_name:
+                return False
+            return get_file_version(file_name).isdigit()
+
+        files = filter(is_version_file, os.listdir(cls.migrate_location))
+        return sorted(files, key=lambda x: int(get_file_version(x)))
 
     @classmethod
     def _get_model(cls, model: str) -> Type[Model]: