gcc 15: fix listElementDelete prototype definition

[cscd98]

Fix compiling under GCC 15.

Issue:

deps/libShake/src/common/helpers.c:19:14: error: conflicting types for ‘listElementDelete’; have ‘ListElement *(ListElement *, ListElement *, void (*)(void *))’
   19 | ListElement *listElementDelete(ListElement *head, ListElement *toDelNode, void(*itemDel)(void *item))
      |              ^~~~~~~~~~~~~~~~~
In file included from deps/libShake/src/common/helpers.c:1:
deps/libShake/src/common/helpers.h:11:14: note: previous declaration of ‘listElementDelete’ with type ‘ListElement *(ListElement *, ListElement *, void (*)(void))’
   11 | ListElement *listElementDelete(ListElement *head, ListElement *toDelNode, void(*itemDel)());