Adjust tests to IPv6-enabled HTTP::Proxy. The patch from https://rt.cpan.org/Public/Bug/Display.html?id=120275 adds IPv6 support to HTTP::Proxy (in Debian added as HTTP-Proxy-0.304-Support-IPv6.patch in libhttp-proxy-perl since 0.304-4). . As HTTP::Proxy listens by default on 'localhost', the three tests t/100_low/08_proxy.t, t/100_low/18_no_proxy.t, t/100_low/32_proxy_auth.t now fail, as they expect the proxy to run on 127.0.0.1 whereas localhost can be ::1 now. . Change the three tests to run the proxy server explicitly on 127.0.0.1.
