Use `git-secure-tag` for releases

[indutny]

This provides stronger security guarantees for signed tags, will also make things more secure for gypkg 😉

See: nodejs/node#7603
See: https://github.com/indutny/git-secure-tag

cc @mscdex @jasnell

[jasnell]

+1 SGTM

[indutny]

Here goes first release https://github.com/nodejs/http-parser/releases/tag/v2.7.1 with git-secure-tag.

Thanks!