No. Comic Life 2 will not support the new OS X 10.10.3 "Photos" app.
If you choose to convert your iPhotos library to "Photos", then Comic Life 2 will not detect the new "Photos" library.
Comic Life 2 is no longer receiving updates.
You may like to upgrade to Comic Life 3 - it costs USD$14.99 - and you can do so here.
Alternatively, a suggested workaround - is to drag from Photos to Desktop (or another location) and then into Comic Life 2.