Update Cubos URL and mark it as discontinued (#1423)

The repo says its no longer being worked on
Fixes https://codeberg.org/ethical-foss/open-slopware/issues/1414

Reviewed-on: https://codeberg.org/ethical-foss/open-slopware/pulls/1423
Reviewed-by: Ethical FOSS admin <ethical-foss-admin@noreply.codeberg.org>

README.md

@@ -1306,7 +1306,7 @@ A desktop environment usually depends on a specific window manager to work.
 | [GDevelop](https://gdevelop.io/) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) | [![AI Functionality](./badges/ai-functionality.svg)](#ai-functionality) ([1](https://wiki.gdevelop.io/gdevelop5/interface/ai/)) <br /> [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://gdevelop.io/), [2](https://github.com/4ian/GDevelop/commit/6ec16045d140a9d55721f71620e128d4969c5fe6), [3](https://github.com/4ian/GDevelop/pull/8509/commits/74409a280cd248ee4d54523b23f5c1507d6380af)) | [Pandemonium Engine] |
 | [GZDoom](https://github.com/zdoom/gzdoom) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/ZDoom/gzdoom/commit/584af500736b0317e42824f39285ed3d954fc4e2)) | [UZDoom](https://github.com/UZDoom/UZDoom), [Chocolate Doom](https://www.chocolate-doom.org/) |
 | [jMonkeyEngine](https://jmonkeyengine.org/)| [`3.6.1-stable`](https://github.com/jMonkeyEngine/jmonkeyengine/releases/tag/v3.6.1-stable) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) [(1)](https://github.com/jMonkeyEngine/jmonkeyengine/pull/2640) <br /> [![AI Code Reviews](./badges/ai-code-reviews-purple.svg)](#ai-code-reviews) [(1)](https://github.com/jMonkeyEngine/jmonkeyengine/pull/2640#issuecomment-4039106977) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) |
-| [Luanti](https://luanti.org) | [`5.14.0`](https://github.com/luanti-org/luanti/releases/tag/5.14.0) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/luanti-org/luanti/pull/16808), [2](https://github.com/luanti-org/luanti/pull/16961), [3](https://github.com/luanti-org/luanti/pull/17095)) | [ClassiCube](https://www.classicube.net/) <br /> [Cubyz](https://github.com/PixelGuys/Cubyz) <br /> [Cubos](https://cubosengine.org) |
+| [Luanti](https://luanti.org) | [`5.14.0`](https://github.com/luanti-org/luanti/releases/tag/5.14.0) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/luanti-org/luanti/pull/16808), [2](https://github.com/luanti-org/luanti/pull/16961), [3](https://github.com/luanti-org/luanti/pull/17095)) | [ClassiCube](https://www.classicube.net/) <br /> [Cubyz](https://github.com/PixelGuys/Cubyz) <br /> [Cubos](https://github.com/GameDevTecnico/cubos) (discontinued) |
 | [Redot Engine](https://www.redotengine.org/) | [`redot-4.4-stable`](https://github.com/Redot-Engine/redot-engine/releases/tag/redot-4.4-stable) <br />[`0cc500d`](https://github.com/Redot-Engine/redot-engine/commit/0cc500dd14f4f44b8ce86e62b3cdb6ff6232f012) | [![AI Functionality](./badges/ai-functionality.svg)](#ai-functionality) ([1](https://github.com/Redot-Engine/redot-engine/blob/master/doc/mcp-integration.md)) <br />[![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/Redot-Engine/redot-engine/blob/master/AI_POLICY.md#usage)) <br />[![AI Code Reviews](./badges/ai-code-reviews-purple.svg)](#ai-code-reviews) ([1](https://github.com/Redot-Engine/redot-engine/pull/154#pullrequestreview-3625112363), [2](https://github.com/Redot-Engine/redot-engine/pull/1142#pullrequestreview-3625056105), [3](https://github.com/Redot-Engine/redot-engine/pull/1124#pullrequestreview-3598626641)) | [Pandemonium Engine] |
 | [Ren'Py](https://www.renpy.org/) | [`7.4.6.1693`](https://github.com/renpy/renpy/releases/tag/7.4.6.1693) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://nitter.net/renpytom/status/2064433925926142248), [2](https://github.com/renpy/renpy/pull/6939)) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) |
 | [UPBGE](https://upbge.org/) | [`0.36.1`](https://github.com/UPBGE/upbge/releases/tag/v0.36.1) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/UPBGE/upbge/wiki/Release-notes-version-0.50#b-implementation-technique-and-limitations)) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) |