(trivial) move StorageEncryptionVersion and StorageReadWriteError to stored_dict.py

diff --git a/electrum/gui/qt/main_window.py b/electrum/gui/qt/main_window.py
index e5a82b3..81b5ca9 100644
--- a/electrum/gui/qt/main_window.py
+++ b/electrum/gui/qt/main_window.py
@@ -1922,7 +1922,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self.password_button.setVisible(self.wallet.may_have_password())
 
     def change_password_dialog(self):
-        from electrum.storage import StorageEncryptionVersion
+        from electrum.stored_dict import StorageEncryptionVersion
         if StorageEncryptionVersion.XPUB_PASSWORD in self.wallet.get_available_storage_encryption_versions():
             from .password_dialog import ChangePasswordDialogForHW
             d = ChangePasswordDialogForHW(self, self.wallet)
diff --git a/electrum/storage.py b/electrum/storage.py
index 11ea8fe..6accb9c 100644
--- a/electrum/storage.py
+++ b/electrum/storage.py
@@ -28,7 +28,6 @@ import stat
 import hashlib
 import base64
 import zlib
-from enum import IntEnum
 from typing import Optional
 
 import electrum_ecc as ecc
@@ -37,7 +36,6 @@ from . import crypto
 from .util import (profiler, InvalidPassword, WalletFileException, bfh, standardize_path,
                    test_read_write_permissions, os_chmod)
 
-from .wallet_db import WalletDB
 from .logging import Logger
 
 
@@ -47,13 +45,9 @@ def get_derivation_used_for_hw_device_encryption():
             "/1112098098'")  # ascii 'BIE2' as decimal
 
 
-class StorageEncryptionVersion(IntEnum):
-    PLAINTEXT = 0
-    USER_PASSWORD = 1
-    XPUB_PASSWORD = 2
+from .stored_dict import StorageEncryptionVersion, StorageReadWriteError
 
 
-class StorageReadWriteError(Exception): pass
 
 
 class StorageOnDiskUnexpectedlyChanged(Exception): pass
diff --git a/electrum/stored_dict.py b/electrum/stored_dict.py
index bbf0b95..3879126 100644
--- a/electrum/stored_dict.py
+++ b/electrum/stored_dict.py
@@ -25,6 +25,7 @@
 
 import threading
 import json
+from enum import IntEnum
 from collections import defaultdict
 from typing import TYPE_CHECKING, Optional, Sequence, List, Union, Any
 
@@ -34,6 +35,12 @@ if TYPE_CHECKING:
     from .storage import WalletStorage
 
 
+class StorageReadWriteError(Exception): pass
+
+class StorageEncryptionVersion(IntEnum):
+    PLAINTEXT = 0
+    USER_PASSWORD = 1
+    XPUB_PASSWORD = 2
 
 
 def locked(func):
diff --git a/electrum/wallet.py b/electrum/wallet.py
index 0de4221..70573de 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -63,7 +63,8 @@ from .keystore import (
 )
 from .simple_config import SimpleConfig
 from .fee_policy import FeePolicy, FixedFeePolicy, FEE_RATIO_HIGH_WARNING, FEERATE_WARNING_HIGH_FEE
-from .storage import StorageEncryptionVersion, WalletStorage
+from .stored_dict import StorageEncryptionVersion
+from .storage import  WalletStorage
 from .wallet_db import WalletDB
 from .transaction import (
     Transaction, TxInput, TxOutput, PartialTransaction, PartialTxInput, PartialTxOutput, TxOutpoint, Sighash