fix(typings): make `Transactionable` compatible with `TransactionOptions` (#13334)

Co-authored-by: Pedro Augusto de Paula Barbosa <papb1996@gmail.com>

types/lib/transaction.d.ts

@@ -149,7 +149,7 @@ export interface TransactionOptions extends Logging {
   /**
    * Parent transaction.
    */
-  transaction?: Transaction;
+  transaction?: Transaction | null;
 }
 
 export default Transaction;

types/test/models/User.ts

@@ -110,6 +110,11 @@ User.addHook('beforeFind', 'test', (options: FindOptions<UserAttributes>) => {
   return undefined;
 });
 
+User.addHook('afterDestroy', async (instance, options) => {
+  // `options` from `afterDestroy` should be passable to `sequelize.transaction`
+  await instance.sequelize.transaction(options, async () => undefined);
+});
+
 // Model#addScope
 User.addScope('withoutFirstName', {
   where: {