flatpak: Pin down 240p-test-suite-ps1 commit

The next commit removes prebuilt files.
3 jobs for wip/exalm/240p in 44 minutes and 35 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed flatpak #1059209
flatpak

00:40:19

passed tests #1059289
flatpak

00:04:16

failed tests #1059208
flatpak

00:00:26