Allow for author names with white spaces

[gvdr]

Fixed filename.jl so that it can handle author family names with white spaces.

It does that by stripping all white spaces in the filename.

The fix solves an issues with pandoc, that would result in a file not found error.

[tpoisot]

I'm going to close this one for now because all the building steps are moving to https://github.com/PoisotLab/manuscript-typesetter/ (I've already made the change there, and it will be accessible when #16 is merged)

[tpoisot]

🎉 the version currently on main has this fix (and so, so much more)

[gvdr]

Amazing! 🤾🤾🤾