make sure SQL IN works with python set

lbry/wallet/database.py

@@ -140,7 +140,7 @@ def constraints_to_sql(constraints, joiner=' AND ', prepend_key=''):
             if constraint:
                 if isinstance(constraint, (list, set, tuple)):
                     if len(constraint) == 1:
-                        values[f'{key}{tag}'] = constraint[0]
+                        values[f'{key}{tag}'] = next(iter(constraint))
                         sql.append(f'{col} {one_val_op} :{key}{tag}')
                     else:
                         keys = []

tests/unit/wallet/test_database.py

@@ -99,7 +99,7 @@ class TestQueryBuilder(unittest.TestCase):
             })
         )
         self.assertTupleEqual(
-            constraints_to_sql({'txo.name__in': ('abc123',)}),
+            constraints_to_sql({'txo.name__in': {'abc123'}}),
             ('txo.name = :txo_name__in0', {
                 'txo_name__in0': 'abc123',
             })