Installer fails when creating manual partitions with gparted

### What Happened?

I selected manual partition, with gparted: 300 mb fat32, 30 gb ext4, and 2 gb swap. Then I told the installer to use these as /boot, / and /swap respectively. The installer failed, the error message was that these were not GPT partitions.

### Steps to Reproduce

Described above

### Expected Behavior

For gparted to create gpt partitions automatically, if these are required. That's a nuance that most people, even experienced people, will miss when creating these new partitions.

### OS Version

8.x (Early Access)

### Session Type

Classic Session (X11, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

_No response_