Avoid string overflow warning

Use xStrdup instead of xMallow and strncpy

    StringUtils.c: In function ‘String_split’:
    StringUtils.c:86:7: error: ‘strncpy’ specified bound depends on the length of the source argument [-Werror=stringop-overflow=]
       86 |       strncpy(token, s, size + 1);
          |       ^
    StringUtils.c:84:18: note: length computed here
       84 |       int size = strlen(s);
          |                  ^

StringUtils.c

@@ -81,10 +81,7 @@ char** String_split(const char* s, char sep, int* n) {
       s += size + 1;
    }
    if (s[0] != '\0') {
-      int size = strlen(s);
-      char* token = xMalloc(size + 1);
-      strncpy(token, s, size + 1);
-      out[ctr] = token;
+      out[ctr] = xStrdup(s);
       ctr++;
    }
    out = xRealloc(out, sizeof(char*) * (ctr + 1));