Fix for localhost vs IP cypress testing issue

[krachwal]

Well this was an odd one... The React frontend could interact with the Python backend using localhost when the Analyze button was click. Cypress performing the same button click did not trigger a call to the Python API. My initial fix was changing the url invoked by the button click to 127.0.0.1 instead of localhost, but the IP didn't sit right with me. I tried several other fixes, but enabling ipv4first is the only one that worked. This is due to a fairly recent change to NodeJS documented here and further explained here as setting verbatim to false in dns lookup, which prioritized ipv4 addresses over ipv6:

verbatim When true, the callback receives IPv4 and IPv6 addresses in the order the DNS resolver returned them. When false, IPv4 addresses are placed before IPv6 addresses. Default: true (addresses are not reordered).