Typing: hash64 missing x64arch argument

[tcmitchell]

The code for mmh3_hash64 in mmh3module.c has a x64arch argument, but the typing file __init__.pyi does not declare this as an argument to hash64. The result is a mypy error if code uses the x64arch keyword argument.

[hajimes]

Thank you so much for reporting the problem. A fix to this issue was released in 4.1.0. Incidentally, I was able to find another bug on s390x (#52) when testing the fix to this issue, so your report is doubly appreciated.