How do I convert this rule to action?

As rule is deprecating in near future, I want to convert this rule to action:

function (user, context, callback) {

  user.awsRole = 'arn:aws:iam::1234567890:role/Auth0v2,arn:aws:iam::1234567890:saml-provider/Auth0';
  user.awsRoleSession = user.name;

  context.samlConfiguration.mappings = {
    'https://aws.amazon.com/SAML/Attributes/Role': 'awsRole',
    'https://aws.amazon.com/SAML/Attributes/RoleSessionName': 'awsRoleSession'
  };

  callback(null, user, context);

}

I tried to convert it as following for action:

exports.onExecutePostLogin = async (event, api) => {
 const user = event.user;
  user.awsRole = 'arn:aws:iam::1234567890:role/Auth0v2,arn:aws:iam::1234567890:saml-provider/Auth0';
};

However it shows the warning:

Property 'awsRole' does not exist on type 'User & { multifactor?: string[] | undefined; } & { identities: UserIdentity[]; }'.(2339)

This worked for me:

exports.onExecutePostLogin = async (event, api) => {
  api.samlResponse.setAttribute("https://aws.amazon.com/SAML/Attributes/Role", "arn:aws:iam::1234567890:role/Auth0v2,arn:aws:iam::1234567890:saml-provider/Auth0");
  api.samlResponse.setAttribute("https://aws.amazon.com/SAML/Attributes/RoleSessionName", event.user.name);
};

Good general info here on migrating from rules to actions, and check out these references on the event and api objects