Fix duplicate variable name bug

I should've picked a better variable name last commit.

init.lua

@@ -67,8 +67,8 @@ end)
 -- Send achievements
 if awards then
     awards.register_on_unlock(function(name, def)
-        local name = def.name or def.title or "N.A."
-        matrix.send(http_api, name .. "has made the achievement [" .. name .. "]")
+        local award_name = def.name or def.title or "N.A."
+        matrix.send(http_api, name .. "has made the achievement [" .. award_name .. "]")
     end)
 end