util/path: fix compile warning

util-path.c:251:11: error: initializing 'char *' with an expression of type 'const char *' discards qualifiers
      [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
  251 |     char *final = strrchr(path, DIRECTORY_SEPARATOR);
      |           ^       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

src/util-path.c

@@ -248,7 +248,7 @@ const char *SCBasename(const char *path)
     if (!path || strlen(path) == 0)
         return NULL;
 
-    char *final = strrchr(path, DIRECTORY_SEPARATOR);
+    const char *final = strrchr(path, DIRECTORY_SEPARATOR);
     if (!final)
         return path;