Fix flaky tests

[zerolab]

test_get_split_content_splits_longer_content is a bit flaky and sometimes splits == 1 resulting in

    def test_get_split_content_splits_longer_content():
        content_length = 340
        split_length = 200
        body = fake.text(max_nb_chars=content_length)[:content_length]
        instance = ExamplePageFactory.create(title="a", body=body)
        splits = instance._get_split_content(split_length=split_length, split_overlap=0)
>       assert len(splits) == 2
E       AssertionError: assert 1 == 2
E        +  where 1 = len(['a\nPainting right various sort. Western medical cut third of song hotel social. Early young with from form dog hand.\nStyle though rest home shoulder agency. Own use look blue film loss enough.'])

most prononunce in CI, but had it locally a few times

[zerolab]

I believe this was fixed by #24 /cc @tm-kn

[tm-kn]

Haven't seen evidence of tests failing randomly in a while. Closing.