Support Linux Gentoo

[Norbiros]

Problem

Prisma works correctly, but I get this warning:

Prisma doesn't know which engines to download for the Linux distro "gentoo". Falling back to Prisma engines built "debian".
Please report your experience by creating an issue at https://github.com/prisma/prisma/issues so we can add your distro to the list of known supported distros.

Suggested solution

Add Gentoo to list of supported distros

Additional context

[chrismurtagh]

Same here with prisma 4.14.1

[systemadmax]

the probleme still exist in 4.15.0

[timovolkmer]

Same here. Prisma 4.16.0 works with gentoo.

[Baconing]

prisma 5.0.0 aswell

[eugenmihailescu]

Same here. Prisma 5.10.2 works in my Gentoo Linux 2.14.

[Jolg42]

I'll close this, as the fallback/default engine should work as expected, so only a report would be needed if there is an issue, let us know if that's the case.

Note that we changed the message, to make it informational only in #23243
The updated message will be part of the next release 5.11.0, next week.