bump selfsigned to 2.1.1 (and bump node-forge to ^1.3.1 as sub-dependency)

[pavel-voronin]

Summary of changes

There is a [email protected] dependency with [email protected] sub-dependency which is vulnerable a lot. I have bumped selfsigned to the latest version and checked that nothing was broken.

Relinquishment of Rights

Please mark following checkbox to confirm that you relinquish all rights of your changes:

• [x] I waive and relinquish all rights regarding this changes (including code, text, and images) to Deepkit UG (limited), Germany. This changes (including code, text, and images) are under MIT license without name attribution, copyright notice, and permission notice requirement.

[pavel-voronin]

@marcj ping

[marcj]

Thanks!