Add neotest-golang to README

[fredrikaverpil]

I've made another adapter for Go, in fredrikaverpil/neotest-golang, as I was having a lot of issues with the one listed in the README. My adapter outlines those problems here.

I figured it could be helpful for others to list my adapter as an alternative, for others who might also have issues with the currently listed Go adapter. 😄

[quolpr]

@fredrikaverpil great adapter! Thanks, added to my nvim config.

Hope your PR will be merged soon

[rcarriga]

Great thank you! I do intend to look at replacing the original if yours covers the same functionality, also good to hear others find it better :raised_hands: