replace package-query with expac

[excalibur1234]

there are only a couple of instances, where package-query is really needed in pacuis code. but they could all get replaced with expac.

pros:

• pacaur already depends on expac
• expac is a smaller package

neutral:

• both are still maintained
• preliminary tests show that both perform with about the same speed.

[excalibur1234]

done in 48f38037a913b29fbb859df166c78e78e03f173e