changed username to display_name

db/mycroft/account_schema/tables/account.sql

@@ -1,7 +1,7 @@
 CREATE TABLE account.account (
     id                  uuid        PRIMARY KEY DEFAULT gen_random_uuid(),
     email_address       text        NOT NULL UNIQUE,
-    username            text        NOT NULL UNIQUE,
+    display_name       text        NOT NULL UNIQUE,
     password            text,
     insert_ts           TIMESTAMP   NOT NULL DEFAULT CURRENT_TIMESTAMP
 );