postgres: remove not null constraint on data column of record changes table (#3594)

pkg/storage/postgres/migrate.go

@@ -128,6 +128,17 @@ var migrations = []func(context.Context, pgx.Tx) error{
 			return err
 		}
 
+		return nil
+	},
+	4: func(ctx context.Context, tx pgx.Tx) error {
+		_, err := tx.Exec(ctx, `
+			ALTER TABLE `+schemaName+`.`+recordChangesTableName+`
+			ALTER data DROP NOT NULL
+		`)
+		if err != nil {
+			return err
+		}
+
 		return nil
 	},
 }