Fix remaining memory bugs

[Xmader]

The CI sometimes fail on main even after we released the "stable" PythonMonkey v1.0.

After all pytests are done, the program segfaults during the Python interpreter finalization.

============================= 678 passed in 23.59s =============================
/Users/runner/work/_temp/cab3e84e-a831-4a41-9c31-79102f1651a5.sh: line 7:  5781 Segmentation fault: 11  (core dumped) poetry run python -m pytest tests/python

---

Debugged using a debug build of Python

[Xmader]

* thread #1, name = 'python', stop reason = signal SIGSEGV: address not mapped to object
  * frame #0: 0x0000ffff97f6acf8 libpython3.11.so.1.0`PyObject_GC_Del [inlined] gc_list_remove(node=0x0000ffff9124d2b0) at gcmodule.c:269:5
    frame #1: 0x0000ffff97f6acf8 libpython3.11.so.1.0`PyObject_GC_Del(op=0x0000ffff9124d2c0) at gcmodule.c:2350:9
    frame #2: 0x0000ffff97f02d34 libpython3.11.so.1.0`maybe_freelist_clear(interp=0x0000ffff982706d0, fini=0) at tupleobject.c:1251:13
    frame #3: 0x0000ffff9800cee0 libpython3.11.so.1.0`gc_collect_main [inlined] clear_freelists(interp=0x0000ffff982706d0) at gcmodule.c:1037:5
    frame #4: 0x0000ffff9800ced8 libpython3.11.so.1.0`gc_collect_main(tstate=0x0000ffff9828aa50, generation=2, n_collected=0x0000000000000000, n_uncollectable=0x0000000000000000, nofail=1) at gcmodule.c:1313:9
    frame #5: 0x0000ffff9800d5a4 libpython3.11.so.1.0`_PyGC_CollectNoFail(tstate=<unavailable>) at gcmodule.c:2110:9
    frame #6: 0x0000ffff97ffd2a0 libpython3.11.so.1.0`Py_FinalizeEx at pylifecycle.c:1833:5
    frame #7: 0x0000ffff9800b788 libpython3.11.so.1.0`Py_RunMain at main.c:682:9
    frame #8: 0x0000ffff9800b468 libpython3.11.so.1.0`Py_BytesMain(argc=<unavailable>, argv=<unavailable>) at main.c:734:12
    frame #9: 0x0000ffff97bb73fc libc.so.6`___lldb_unnamed_symbol2962 + 108
    frame #10: 0x0000ffff97bb74cc libc.so.6`__libc_start_main + 152
    frame #11: 0x0000aaaade3e08b0 python3.11`_start + 48