remove format specifies type unmatch warning
remove format specifies type unmatch warning

```
citrine.c:81:86: warning: format specifies type 'unsigned long' but the argument has type 'uint64_t' (aka 'unsigned long long')
      [-Wformat]
                printf( "[WARNING] Citrine has detected an internal memory leak of: %lu bytes.\n", ctr_gc_alloc );
                                                                                    ~~~            ^~~~~~~~~~~~
                                                                                    %llu
```

gabordemooij/citrine,gabordemooij/citrine,gabordemooij/citrine