Build: Port to 1.21.5 Forge+NeoForge

Also bumps 1.21.5 Fabric to build against the 1.21.5 release version, so
remapping to the new projects works properly.

Author: Johni0702

README.md

@@ -74,6 +74,9 @@ done
             <img alt="standalone" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-standalone/maven-metadata.xml">
           </td>
         </tr>
+        <tr><td>1.21.5</td><td>neoforge</td><td><img alt="1.21.5-neoforge" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.5-neoforge/maven-metadata.xml"></td></tr>
+        <tr><td>1.21.5</td><td>forge</td><td><img alt="1.21.5-forge" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.5-forge/maven-metadata.xml"></td></tr>
+        <tr><td>1.21.5</td><td>fabric</td><td><img alt="1.21.5-fabric" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.5-fabric/maven-metadata.xml"></td></tr>
         <tr><td>1.21.4</td><td>neoforge</td><td><img alt="1.21.4-neoforge" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.4-neoforge/maven-metadata.xml"></td></tr>
         <tr><td>1.21.4</td><td>forge</td><td><img alt="1.21.4-forge" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.4-forge/maven-metadata.xml"></td></tr>
         <tr><td>1.21.4</td><td>fabric</td><td><img alt="1.21.4-fabric" src="https://img.shields.io/badge/dynamic/xml?color=A97BFF&label=%20&query=/metadata/versioning/versions/version[not(contains(text(),'%2B'))][last()]&url=https://repo.essential.gg/repository/maven-releases/gg/essential/universalcraft-1.21.4-fabric/maven-metadata.xml"></td></tr>