ruff

d31d09d7 - Add ``--preview`` to instruction for running newly added tests (#9846)

Add ``--preview`` to instruction for running newly added tests (#9846) ## Summary This surprised me while working on adding a test. I thought about adding an additional `note`, but how often is this incorrect? In general, people reading the contributing guidelines probably want to enable this flag and those who don't will know enough about the testing setup to have their own commands/aliases. ## Test Plan Ran CI on local fork and got an all green.