set PDF preference to print without scaling

[Wooble]

When printing labels, it's important to not scale the page, but many PDF viewers default to doing so anyway. This would have ReportLab set the Viewer Preference for no print scaling.

[command-tab]

@bcbnz Any plans to merge this?

Thanks!

[command-tab]

Merge please? 🙏🏻

[command-tab]

Still hoping for a merge on this. It's been causing a minor annoyance in one my apps for some time, and I'm hoping to not have to maintain a fork of this excellent library just for a one-line change. Thank you!