tracker: switch to the 2.3 branch of tracker
Work started on the 3.0 version on the main branch, so we need to switch the elements to track the stable 2.3 branch that every application currnetly uses.
Once applications start using tracker 3.0 and the developers think its ready for testing we can/should include another element along side 2.3 like we do for gtk4.
Edited by Jordan Petridis