db: check for change using address strings only

Comparing the address itself includes the network, but an
unchecked signet address will have its network set as testnet
by `assume_checked` and so change addresses will not be
matched.

src/database/mod.rs

@@ -243,7 +243,7 @@ impl DatabaseConnection for SqliteConn {
         self.db_address(address).map(|db_addr| {
             (
                 db_addr.derivation_index,
-                address == &db_addr.change_address.assume_checked(),
+                address.to_string() == db_addr.change_address.assume_checked().to_string(),
             )
         })
     }