main: Fix string leak in setupLog

Leak report

10 bytes in 1 blocks are definitely lost in loss record 478 of 10,205
   at 0x48447A8: malloc (vg_replace_malloc.c:446)
   by 0x5AAE661: g_malloc (gmem.c:100)
   by 0x136811: g_strdup_inline (gstrfuncs.h:317)
   by 0x136811: setupLog (main.c:119)
   by 0x136811: main (main.c:689)

Testing

• No issues were detected with Valgrind when testing the patch