Feature: Support falling back to multiple DNS servers from DNS config. (#257 by @clue)

If you're using the default Connector, it will now use all DNS servers configured on your system. If you have multiple DNS servers configured and connectivity to the primary DNS server is broken, it will now fall back to your other DNS servers, thus providing improved connectivity and redundancy for broken DNS configurations.

Feature: Use round robin for happy eyeballs DNS responses (load balancing). (#247 by @clue)

If you're using the default Connector, it will now randomize the order of the IP addresses resolved via DNS when connecting. This allows the load to be distributed more evenly across all returned IP addresses. This can be used as a very basic DNS load balancing mechanism.

Internal improvement to avoid unhandled rejection for future Promise API. (#258 by @clue)

Improve test suite, use GitHub actions for continuous integration (CI). (#254 by @SimonFrings)