Transaction prevention

Hi,

If I have a user that is restricted to select access (only) on a single
table, is there any way to prevent that user from starting a transaction?

The reason for the question is that the select-only user can block another
session trying to run an alter table on that table if the select-only
user runs their query in a transaction.

This happened to us recently where a migration script that was being run
during a ci deployment 'hung' until the select-only user happened to
disconnect. I'm wondering if we need to terminate any sessions from
select-only users at the start of the migration, or if there is a better
way.

Thanks,

Steve