Replaced i18n.t w/ tpl helper in v3/posts.js file (#13580)
Replaced i18n.t w/ tpl helper in v3/posts.js file (#13580)

refs: #13380

- The i18n package is deprecated. It is being replaced with the tpl package.
ErisDS/Ghost,janvt/Ghost,e10/Ghost,TryGhost/Ghost,janvt/Ghost,ErisDS/Ghost,TryGhost/Ghost,TryGhost/Ghost,e10/Ghost,ErisDS/Ghost