gui: fix ruff I001 import sort order in dialogs.py

The i18n merge left BalanceTooLowException and BalTimestamp out of order
in the .common import block, so ruff check bal/ tests/ was no longer
clean. Swapped the two lines; no behaviour change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

bal/gui/qt/dialogs.py

@@ -65,8 +65,8 @@ from .common import (
     N_,
     AmountException,
     Any,
-    BalTimestamp,
     BalanceTooLowException,
+    BalTimestamp,
     BestEffortRequestFailed,
     Buttons,
     Callable,