port to ECM's FindCanberra

Summary:
- bump required kf5 version to 5.56
- use new VERSION var in FindCanberraPulse
- use new imported target when linking

Test Plan: cmake && make successful

Reviewers: apol

Reviewed By: apol

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D19382