Install instructions refer to deleted requirements.txt

[claumer]

Hi there,

I'm just trying to install and test freebarcodes for the first time, and by following the install instructions as listed in the readme, I get:

ERROR: Could not open requirements file: [Errno 2] No such file or directory: 'requirements.txt'

Could you please update the install recommendations, if this requirements file is indeed no longer needed? (I notice it has been deleted in a recent commit).

Regards,
Chris L