I ran the following code (for demo purposes): ``` import pydracor corpus = pydracor.Corpus('fre') corpus.summary() ``` At the last line I had an error: `ValueError: invalid literal for int() with base 10: '1678-02-25'` I also attach a screenshot <img width="864" alt="Screenshot 2024-02-12 at 11 39 35" src="https://github.com/dracor-org/pydracor/assets/19728469/f204ab55-a5ed-42cc-9382-e6bfaa3abe9b">