Do not shade the MultiMap class

This class is used by ProtocolLib. Calling it, means we use its signature. With relocating this would also update the method
call signature to `.WrappedGameProfile.getProperties()Lfastlogin/guava/collect/Multimap;`, which obviously not present.

Author: games647

bukkit/pom.xml

@@ -71,6 +71,9 @@
                         <relocation>
                             <pattern>com.google.common</pattern>
                             <shadedPattern>fastlogin.guava</shadedPattern>
+                            <excludes>
+                                <exclude>com.google.common.collect.Multimap</exclude>
+                            </excludes>
                         </relocation>
                         <relocation>
                             <pattern>io.papermc.lib</pattern>