TLSv1 used for connections

PROTOCOL_TLSv1 is referenced in: https://gitlab.developers.cam.ac.uk/uis/devops/django/ucamlookup/blob/0a1b36ad51d086ba3678a9ee8dd8876ac4f4f15c/ucamlookup/ibisclient/connection.py#L110 https://gitlab.developers.cam.ac.uk/uis/devops/django/ucamlookup/blob/0a1b36ad51d086ba3678a9ee8dd8876ac4f4f15c/ucamlookup/ibisclient/connection.py#L140

TLS 1.0 is considered unsecured and a better option should be to specify a minimum version and let the protocol to negotiate instead of specify a fixed version.