`SupportedRegion` is missing tier 2 regions

[jhuleatt]

Tier 2 regions should be included in SupportedRegion:

firebase-functions-python/src/firebase_functions/options.py

Lines 92 to 103 in 59d68cf

	class SupportedRegion(str, _enum.Enum):
	"""
	All regions supported by Cloud Functions v2.
	"""
	ASIA_NORTHEAST1 = "asia-northeast1"
	EUROPE_NORTH1 = "europe-north1"
	EUROPE_WEST1 = "europe-west1"
	EUROPE_WEST4 = "europe-west4"
	US_CENTRAL1 = "us-central1"
	US_EAST1 = "us-east1"
	US_WEST1 = "us-west1"

See firebase/firebase-functions#1397 for more context