test_framework: Py3.4 compat: Specify timeout parameter by name

Changed in version 3.4: The strict parameter was removed. HTTP 0.9-style
“Simple Responses” are not longer supported.
(https://docs.python.org/3/library/http.client.html)

Source: https://github.com/jgarzik/python-bitcoinrpc/commit/7ebeebb4f61917fe590d980cb4f9aefdce2c8f25