Always import qt library before importing qasync for examples.

[christofsteel]

qasync guesses the python qt wrapper it injects itself into, based on the already loaded module or (if no module is available) on the installed python qt wrapper. The latter approach is a good backup, but can lead to errors, when multiple wrappers are installed.

From what I've gathered, importing qasync after the respective qt wrapper is the preferred way to determine the wrapper to use, so examples should reflect this, to avoid usage errors such as christofsteel/syng#8 (comment) 😅