install solc and abigen first:

$ npm install -g solc
$ go install github.com/ethereum/go-ethereum/cmd/abigen@latest

and then execute code generation:

$ cd sns
$ abigen --abi public_resolver.json --pkg sns --type publicResolver --out public_resolver.go
$ abigen --abi base_registrar.json --pkg sns --type baseRegistrar --out base_registrar.go