update class names to official mappings

src/main/java/de/skate702/craftingkeys/manager/AnvilManager.java

@@ -1,7 +1,7 @@
 package de.skate702.craftingkeys.manager;
 
 import de.skate702.craftingkeys.util.Logger;
-import net.minecraft.inventory.container.Container;
+import net.minecraft.world.inventory.AbstractContainerMenu;
 
 /**
  * Manages a Anvil GUI Inventory.
@@ -14,7 +14,7 @@ public class AnvilManager extends ContainerManager {
      *
      * @param container The container from a crafting GUI
      */
-    private AnvilManager(Container container) {
+    private AnvilManager(AbstractContainerMenu container) {
         super(container);
     }
 
@@ -24,7 +24,7 @@ public class AnvilManager extends ContainerManager {
      * @param container A container from a GUI
      * @return manager-singleton
      */
-    public static AnvilManager getInstance(Container container) {
+    public static AnvilManager getInstance(AbstractContainerMenu container) {
         if (instance == null) {
             instance = new AnvilManager(container);
         } else {