Check for updates in pdf viewer dependencies

[bianchimro]

https://github.com/mikecousins/react-pdf-js

see also:

• https://github.com/wojtekmaj/react-pdf
• https://github.com/MGrin/mgr-pdf-viewer-react

[bianchimro]

@uf0 with new version of the package we're using (seems the best option) there is a new option called "fitWidth" (working, while "fillHeight" does not seem to work).

Proposal: we could add a "fit width" button alternative to manual zoom.

[uf0]

it's not possible to add a "fitHeight" button? and by default have the pdf adapted to the width?