Fix test failure on armhf + Qt 6

The following discussion from !44 (merged) should be addressed:

• @peat-psuwit started a discussion:

  3: Qt: Dead lock detected while activating a BlockingQueuedConnection: Sender is QDBusConnectionPrivate(0xf1800ac8), receiver is QDBusConnectionPrivate(0xf1800ac8)

  This feels like a bug somewhere that we shouldn't ignore. Although it might not originate from our code...

  Now, given that Debian freeze is near and it affects only armhf and Qt 6, I'll let it pass for now. I'll create an issue so that we'll look at it someday. Although honestly I have no confidence that that day will actually come...