version.hpp: Pass const reference

In 1fd6ddd it adds a std::string& as parameter, it is better to use
const std::string&.
In the following commit, there is a change that requires const
reference.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: Ie3f350e577d944dd4d7e65a4790b2fead3d7eecb
1 file changed