rules: 'Fixes:' rule rejects URLs with dashes

[bnoordhuis]

✖ 2:7 Fixes must be a GitHub URL. fixes-url

I get this when I try to link to https://github.com/nodejs/node-gyp/issues. Fix in the works.

[richardlau]

Fixed in v3.11.1 via #55.