Update file requirements.txt
This is a very small MR because the current requirement file does not seem to work on python 3.12.3. I tested this requirements file in two different virtualenvs running 3.12.3 and 3.9.16 (yes, I failed to see that 3.8 is still supported; I wanted to cover the range of all supported python versions). Works like a charm in both versions so I assume this fix should work for all.