Add libnss3 package dependency for Debian (plus Ubuntu and Mint)

[jordan-ivpn]

Bug report

On a lightweight Debian system, the libnss3 package is not installed by default, though it is required by ivpn-ui.

Describe your environment

• Device: _____
• OS name and version: Debian 11 netinst
• IVPN app version: 3.3.30

Describe the problem

libnss3 is required by many common desktop environments and is often installed by default, but not all Debian installations use a common DE. A window manager might be used instead.

Steps to reproduce:

1. Install Debian from a lightweight ISO: https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-11.0.0-amd64-netinst.iso
2. Uncheck all "tasks", like the DE and the common system utilities during the install.
3. After installation is complete run apt-cache policy libnss3 to confirm the package is not installed
4. Add a wnidow manager for a graphical experience
5. Install the IVPN App's ivpn-ui package and run it.

Observed Results:

Output:

/opt/ivpn/ui/bin/ivpn-ui: error while loading shared libraries: libnss3.so: cannot open shared object file: No such file or directory

Workaround:

apt install libnss3

Expected Results:

libnss3 needs to be a dependency for the ivpn-ui package.

[stenya]

The libnss3.so is a part of the NSS package which has different names for different distributions. E.g.: libnss (Debian, Ubuntu); nss (Fedora, CentOS).

Usually, this package is installed by default in most distributions. I do not plan (at least for now) to make a hard dependency on this package in order to avoid potential regression after such a change.

I will keep this ticket open. We can back to it if more users will complain about this corner issue.