fix: gofumpt formatting in cmd/dataset.go

[Copilot]

CI was failing on the gofumpt format check (test -z "$(gofumpt -l .)") due to misaligned struct fields in DatasetListItem.

Change

• Align Name and Type fields with LastIngested in DatasetListItem to satisfy gofumpt:

// before
type DatasetListItem struct {
	Name string
	Type string
	LastIngested time.Time
}

// after
type DatasetListItem struct {
	Name         string
	Type         string
	LastIngested time.Time
}

[github-actions]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

_{You can retrigger this bot by commenting recheck in this Pull Request}