SEGFAULT in CI but works locally

[Kishan-Ved]

Description of the problem

In the file: pydatastructs/trees/tests/test_binary_trees.py, inside the _test_SplayTree() function:
There are 2 code snippets which run only when the backend is Python. This is because if we run them in C++ backend, the CI checks fail. However, the code passes when run on my local machine (laptop - Ubuntu).

These are the code snippets:

    if(backend==Backend.PYTHON):
        trav3 = BinaryTreeTraversal(t, backend=backend)
        in_order = trav3.depth_first_search(order='in_order')
        pre_order = trav3.depth_first_search(order='pre_order')
        assert [node.key for node in in_order] == [20, 30, 50, 55, 100, 200, 1000, 2000]
        assert [node.key for node in pre_order] == [200, 55, 50, 30, 20, 100, 2000, 1000]

    if(backend==Backend.PYTHON):
        trav5 = BinaryTreeTraversal(t, backend=backend)
        in_order = trav5.depth_first_search(order='in_order')
        pre_order = trav5.depth_first_search(order='pre_order')
        assert [node.key for node in in_order] == [20, 30, 50, 55, 100, 200]
        assert [node.key for node in pre_order] == [200, 55, 50, 30, 20, 100]

This was added in PR: #562