Update README.md

changed (deprecated) discord invite to valid one, pointing to the room "curious newcomer" as agreed by the consortium steering group

README.md

@@ -24,7 +24,7 @@
   <a href="https://github.com/BioDynaMo/biodynamo/actions/workflows/centos-system-ci.yml"><img src="https://github.com/BioDynaMo/biodynamo/actions/workflows/centos-system-ci.yml/badge.svg"/></a>
   <a href="https://github.com/BioDynaMo/biodynamo/actions/workflows/macos-system-ci.yml"><img src="https://github.com/BioDynaMo/biodynamo/actions/workflows/macos-system-ci.yml/badge.svg"/></a>
   <a href="https://sonarcloud.io/project/overview?id=BioDynaMo_biodynamo"><img src="https://sonarcloud.io/api/project_badges/measure?project=BioDynaMo_biodynamo&metric=alert_status"/></a>
-  <a href="https://discord.gg/9hNCbNYwcT"><img src="https://img.shields.io/discord/1029690454574370816"/></a>
+  <a href="https://discord.com/invite/kTcTTNFy"><img src="https://img.shields.io/discord/1029690454574370816"/></a>
   <a href="https://opensource.org/licenses/Apache-2.0"><img src="https://img.shields.io/badge/License-Apache%202.0-blue.svg"/></a>
 </p>