utcnow is deprecated in python3.12

[kasium]

Environment details

• OS type and version: Linux
• Python version: 3.12.0
• pip version: 23.2.1
• google-api-core version: 2.10.2

Issue

The following code uses utcnow which is deprecated in python 3.12

python-api-core/google/api_core/datetime_helpers.py

Lines 43 to 46 in 405272c

	def utcnow():
	"""A :meth:`datetime.datetime.utcnow()` alias to allow mocking in tests."""
	return datetime.datetime.utcnow()