pj_poi: Fix 'get_lodging_stars' on null category

[amatissart]

if match := self.HOTEL_STARS_REGEX.match(acc.category):

would fail if acc.category is None.

[remi-dupre]

Suggested change

	if acc.category:
	if match := self.HOTEL_STARS_REGEX.match(acc.category):
	return float(match.group("rating"))
	if acc.category and (match := self.HOTEL_STARS_REGEX.match(acc.category)):
	return float(match.group("rating"))

We could also have done that, but this := operator quickly makes things weird and harder to read, I'm not sure what to think of it ^^'