Add missing reference

Signed-off-by: Ian Costanzo <ian@anon-solutions.ca>

Author: ianco

aries_cloudagent/ledger/multiple_ledger/indy_manager.py

@@ -9,6 +9,7 @@
 
 from ...cache.base import BaseCache
 from ...core.profile import Profile
+from ...ledger.base import BaseLedger
 from ...ledger.error import LedgerError
 from ...wallet.crypto import did_is_self_certified