The comments about this question are correct in that you cannot use the copy of GParted that is installed on your system to make a change to sda7, your root partition. That is because GParted cannot modify mounted partitions. Usually you get around this by booting a live disk containing GParted. The questioner makes it clear he does not have access to live media. So what can you do?
The answers to this question How can I resize an ext root partition at runtime? use two approaches that work for increasing the size of a mounted partition. The fdisk
solution deletes the partition first (without deleting the underlying filesystem), then it creates a larger partition, at the same start point as the original. Finally the filesystem is resized to make full use of the enlarged partition. There is also a parted
solution (not GParted) that makes use of its resizepart option.
The other approach to this problem (which is perhaps safer) is to boot live media but rather than place it on a usb/dvd/cd, boot it from an iso file saved on your filesystem somewhere. To do this you add a custom item to grub or systemd-boot, depending on what you use. My question and answer here gives the procedure. How to modify partitions without a live USB/CD
In this case the questioner has free space near, but not adjacent to the partition he wants to enlarge (sda7). The sda5 partition is not mounted so the first step to enlarge sda7 is to boot into the Ubuntu system, open GParted and move sda5 fully to the right. That has the effect of moving the unused space next to sda7. Then it’s a case of choosing one of the approaches described above to enlarge sda7.