Make some minor fixes and improvements to the typedddicts_extra_items test

[rchen152]

I'm in the process of implementing PEP 728 in Pyrefly and noticed a few things that could be improved in the corresponding conformance test.

• The tests for setting closed=False when inheriting from a TypedDict with closed=True or extra_items were also adding an illegal extra item in the subclass. Pyright was correctly flagging the extra item but incorrectly not flagging closed=False, meaning it missed the expected error but generated an unexpected one on the same line. I changed the subclass bodies to pass so that the automated conformance checker can detect the missing errors.
• Most of the errors on specific TypedDict items are marked as allowing to occur on either the class line or the key: type line. I found two that were marked as expected on only the class line, so I changed them to be allowed on either line.
• I didn't see a test for closed=True being forbidden when subclassing a TypedDict with non-read-only extra items, so I added it. Pyright already passes it.
• I also added a test verifying that a type checker flags the case of an item having a type that is incompatible with read-only extra items. Pyright passes this as well.
• The update script emitted a warning about zuban not being installed, so I added zuban to requirements.txt.

[JelleZijlstra]

Maybe use MovieBase2? MovieBase was defined a long way up (line 33) and has ReadOnly extra items, which adds an additional complication. The test immediately above this one probably should also have used MovieBase2.

[rchen152]

I intentionally used MovieBase in order to test ReadOnly extra items; the non-ReadOnly variant is already covered. Do you think it would be better to define a MovieBase3 instead of reusing MovieBase?

[JelleZijlstra]

I think so, it's hard to follow the tests when we reuse something that is defined so far up.

We could also use something other than movies in the test (heresy?).

[rchen152]

Indeed heresy ;) Done.