gthumb: update to 3.6.0
gthumb: update to 3.6.0

Closes #9394.

EaterOfCode/void-packages,necrophcodr/void-packages,juliendehos/void-packages,floGik/void-packages,juliendehos/void-packages,necrophcodr/void-packages,juliendehos/void-packages,floGik/void-packages,kulinacs/void-packages,floGik/void-packages,NeoChontrix/void-packages,EaterOfCode/void-packages,necrophcodr/void-packages,coredumb/void-packages,kulinacs/void-packages,coredumb/void-packages,floGik/void-packages,juliendehos/void-packages,NeoChontrix/void-packages,NeoChontrix/void-packages,NeoChontrix/void-packages,coredumb/void-packages,EaterOfCode/void-packages,EaterOfCode/void-packages,coredumb/void-packages,necrophcodr/void-packages,juliendehos/void-packages,kulinacs/void-packages,kulinacs/void-packages,NeoChontrix/void-packages,EaterOfCode/void-packages,floGik/void-packages,kulinacs/void-packages,coredumb/void-packages,necrophcodr/void-packages,coredumb/void-packages,juliendehos/void-packages,kulinacs/void-packages,NeoChontrix/void-packages,floGik/void-packages