File uploads fail to non-default scopes

The client doesn't include a scope header in file contents PUTs.

	PUT /api/1.0/artifact/164/files/foo/ HTTP/1.1
	Host: debusine.incus
	User-Agent: python-requests/2.32.5
	Accept-Encoding: gzip, deflate, br, zstd
	Accept: */*
	Connection: keep-alive
	Token: [REDACTED]
	Content-Range: bytes */1
	Content-Length: 0

This causes a 404 in the permission check for the artifact.