test: sort the vitest named imports to satisfy eslint

The installer CI runs eslint:check before building and the sort-imports rule
rejected the unsorted import in the new checkForUpdates test, failing the Linux
job (and cancelling the others). Order the members alphabetically.

Author: notluquis

test/unit/app-checkforupdates.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { net } from '../setup/electron-stub';
 import { JupyterApplication } from '../../src/main/app';