software/*: version up urllib3, requests and dependencies
Several softwares were using fixed versions, but versions are also defined in stack/slapos.cfg, so let's use from stack/slapos.cfg which will simplify version management.
This urllib3 has visible changes for us, it no longer send the request path "as is", but normalizes the . and .. which is not what we want in caddy-frontend test, so we adjust the test to use prepared requests, which is the recommended approach for this kind of low level needs. Since prepared requests does not set default user agent "python-requests", tests checking that user agent is in log files have been adjusted to use a dedicated test user agent header.
Another change is that certificates are now verified by default, so we adjust seleniumserver tests to disable certificate validation. jstestnode, already had a patch regarding certificate validation, because we wanted certificates to be validated before it was the default. We just update this patch a bit because we want to keep the optional behaviours of validating against a specific CA or to disable validation