This won't work - even if you were able to install gparted.
You need to unmount any partition to be resized.
Do you have enough space to create a new bigger root partition?
You could restore a full backup of the old root to the new root, on a file by file basis.
Perform a couple of necessary changes to a couple of config files to point to the new partition.
Other people may have simpler or much better ways of accomplishing the above.