mod_s2s_auth_posh: Use unused loop variable for something [luacheck] Saves a function call, shuts up luacheck. In no case does the input list of certificates not result in a list of fingerprints of equal length.

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.