flatpak: Remove unsed tracker-miner build option
The miner_apps build option was removed in tracker-miners-2.2.0 [1].
[1] tracker-miners commit 8920540bc2cc859f tracker-miners!33 (merged)
The miner_apps build option was removed in tracker-miners-2.2.0 [1].
[1] tracker-miners commit 8920540bc2cc859f tracker-miners!33 (merged)