Downgrade NMS revision

This is not a precedent, please see https://www.spigotmc.org/wiki/nms/

By: md_5 <git@md-5.net>

paper-server/pom.xml

@@ -13,7 +13,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <api.version>unknown</api.version>
         <minecraft.version>1.16.4</minecraft.version>
-        <minecraft_version>1_16_R3</minecraft_version>
+        <minecraft_version>1_16_R2</minecraft_version>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
     </properties>