tests/pkg_emlearn: fix compilation
tests/pkg_emlearn: fix compilation

It turns out that the fix for the missing terminating newline is not
robust. This hopefully fixes the issue and resolves the following
error message:

    In file included from /home/maribu/Repos/software/RIOT/tests/pkg_emlearn/main.c:25:
    /home/maribu/Repos/software/RIOT/tests/pkg_emlearn/model.h:7221:36: error: stray '\' in program
     7221 |     /* fix for no newline at eof */\n
          |                                    ^
    /home/maribu/Repos/software/RIOT/tests/pkg_emlearn/model.h:7221:38: error: expected ';' before '_Alignas'
     7221 |     /* fix for no newline at eof */\n
          |                                      ^
          |                                      ;

RIOT-OS/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,RIOT-OS/RIOT