Disable uploading to conda-forge/label/main if sources include other labels

[isuruf]

This section

conda-forge-ci-setup-feedstock/recipe/conda_forge_ci_setup/build_utils.py

Lines 126 to 136 in a1026ad

	upload_to_conda_forge = any(owner == "conda-forge" for owner, _ in channels)
	if upload_to_conda_forge and "channel_sources" in specific_config:
	unknown_channel = False
	allowed_channels = ["conda-forge", "conda-forge/label/", "defaults", "c4aarch64", "c4armv7l"]
	for source_channel in source_channels.split(","):
	for c in allowed_channels:
	if source_channel.startswith(c):
	break
	else:
	print("Uploading to conda-forge with source channel '{}' is not allowed".format(source_channel))
	return

needs to be improved.