According to the library's front page (here) capital 'H' in the format string prints out hours in the 24hr clock format and lower case 'h' gives hours in the 12hr clock format so you should change this line:-
erial.println(clock.dateFormat("Hi", dt)); // outputs 1325
to this:-
erial.println(clock.dateFormat("hi", dt)); // outputs 0125
You might want to add the am/pm indicator to make the line:-
erial.println(clock.dateFormat("hia", dt)); // outputs 0125pm
If you want to lose the leading zero use 'g' instead of 'h'.
As in most things in programming case is important.
Ian