Stop Using `Hub` in `HttpTransport`

[szokeasaurusrex]

We are still using the deprecated Hub in HttpTransport:

sentry-python/sentry_sdk/transport.py

Lines 221 to 223 in 407f651

	from sentry_sdk import Hub
	self.hub_cls = Hub

sentry-python/sentry_sdk/transport.py

Lines 551 to 555 in 407f651

	hub = self.hub_cls.current
	def send_envelope_wrapper():
	# type: () -> None
	with hub:

We should stop using the Hub here, as it is deprecated