Replace pdf-lib

[f1sh1918]

Is your feature request related to a problem? Please describe.
Currently we use a very unsupported pdf-lib for our pdf generation (last release 4years+), so we should switch to better maintained fork.

Describe the solution you'd like

• replace current library by sth well supported f.e. this fork. ttps://github.com/cantoo-scribe/pdf-lib
• test if all current pdf generations still work