Preview style: Crash on walrus in with statement

[JelleZijlstra]

This crashes in 23.1a1:

async def f():
    with (x := await sleep(0)):
        pass

Reported by @Zac-HD in #3407 (comment).

[JelleZijlstra]

Some similar crashes that my PR doesn't solve:

% black --preview -c '''
async def f():
    with (x := await a, y := await b): pass
'''

async def f():
    with (x := await a, y := await b): pass
error: cannot format <string>: Cannot parse: 2:11:     with x := await a, y := await b:

% black --preview -c 'for (x := 3, y := 4) in y: pass'       
for (x := 3, y := 4) in y: pass
error: cannot format <string>: Cannot parse: 1:6: for x := 3, y := 4 in y:

[JelleZijlstra]

The first crash in the above comment is actually solved. The second appears to be invalid syntax on 3.11 so not worth spending more time on.