[pkg] Use Twisted < 16.0.0
We have some test failures with 16.0.0, such as:
- test_put_content (unittest_server.ETwistHTTPTC)
- test_base_url (unittest_httptest.TwistedCWAnonTC)
(grafted from 10c12f31d0fe38c2e8814176fc42bf2ea210efdf)
if versions_map['cubicweb'][0] == (3, 7, 4):
config['http-session-time'] *= 60
config['cleanup-session-time'] *= 60
config['cleanup-anonymous-session-time'] *= 60