Port to GTK 4

[danirabbit]

Fixes #628

[danirabbit]

Tested the constraint layout with a number of different partitions with small and large partitions on either end and with unused space:

[ryonakano]

We also need to update the dependencies in README :)

[danirabbit]

@ryonakano done!

[zeebok]

Just tried testing this and noticed this missing icon?

EDIT: After updating my VM and grabbing gparted so I could test the partition view, it is showing up so maybe not a problem. The fact the gparted's UI is opening and partition view showing up, it may just be something with my VM environment.

[zeebok]

Nothing in the code sticks out, and running in test mode worked well except for some reason trying to modify partitions just opened gparted on my machine. But I assume that is just from me running it locally instead of in a normal live session or in VM

[danirabbit]

@zeebok ah yeah "modify" always opens gparted. There's no partition resizing here. You can only choose what to apply on each partition but can't resize or create or delete partitions