Change CI tests to run against pg 11.12, 12.7 and 13.3.
The latest postgres versions adjusts the event_trigger test to
output the list of currently defined event triggers making the
test output different when timescaledb is installed since we
define our own event triggers. Due to this change we have to
ignore the result of this test in our CI.
https://github.com/postgres/postgres/commit/f3c45378
45384357bd