[libkwineffects] Bump API version

Summary:
Recently, libkwineffects got some changes that break ABI compatibility,
so we have to bump the API version.

Test Plan:
When using a binary effect, which is made against 226 version, KWin no
longer crashes.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D17444