Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/go/versions.

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/sz746n0jm0n8dnv47d7cqvwny8ncfbi4-go-1.10.3/bin/gofmt had a zero exit code or showed the expected version
- /nix/store/sz746n0jm0n8dnv47d7cqvwny8ncfbi4-go-1.10.3/bin/.go-wrapped passed the binary check.
- /nix/store/sz746n0jm0n8dnv47d7cqvwny8ncfbi4-go-1.10.3/bin/go passed the binary check.
- 2 of 3 passed binary check by having a zero exit code.
- 0 of 3 passed binary check by having the new version present in output.
- found 1.10.3 with grep in /nix/store/sz746n0jm0n8dnv47d7cqvwny8ncfbi4-go-1.10.3
- directory tree listing: https://gist.github.com/499abd38cfb9318ba6bbcd885951c6b8
- du listing: https://gist.github.com/04fbe15eac23c814fa6b313c8e543e4c

go: 1.10.2 -> 1.10.3