Update CONTRIBUTING.md, our discord links were temporary 7 days valid only, use no limit invos

Author: AnastaZIuk

CONTRIBUTING.md

@@ -60,7 +60,7 @@ Below are some tasks that are open for contribution. If you start working on a t
 
  **[Issues](https://github.com/Devsh-Graphics-Programming/Nabla/issues) also count as free tasks.** We also have old issues from previous generation **[here](https://github.com/buildaworldnet/IrrlichtBAW/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc)**.
 
-If you have questions about the list, you can ask directly on our [Discord server](https://discord.gg/SsJzqS23) or open an issue [here](https://github.com/Devsh-Graphics-Programming/Nabla/issues).
+If you have questions about the list, you can ask directly on our [Discord server](https://discord.gg/Dx83Cu7suD) or open an issue [here](https://github.com/Devsh-Graphics-Programming/Nabla/issues).
 
 ## Pull Request Process
 
@@ -78,7 +78,7 @@ If you have questions about the list, you can ask directly on our [Discord serve
 
 ## Connect with Other Project Contributors
 
-Join our [Discord server](https://discord.gg/SsJzqS23) to connect with other contributors. It's the first place to go for questions and discussions about the project.
+Join our [Discord server](https://discord.gg/Dx83Cu7suD) to connect with other contributors. It's the first place to go for questions and discussions about the project.
 
 ## License