Update to Kotlin 1.9.20, AGP 8.4.0, and Gradle 8.6

app/src/main/java/org/thoughtcrime/securesms/megaphone/Megaphones.java

@@ -398,6 +398,7 @@ public final class Megaphones {
         .build();
   }
 
+  @SuppressLint("NewApi")
   public static @NonNull Megaphone buildGrantFullScreenIntentPermission(@NonNull Context context) {
     return new Megaphone.Builder(Event.GRANT_FULL_SCREEN_INTENT, Megaphone.Style.BASIC)
         .setTitle(R.string.GrantFullScreenIntentPermission_megaphone_title)

app/src/main/java/org/thoughtcrime/securesms/util/views/SlideUpWithSnackbarBehavior.java

@@ -1,5 +1,6 @@
 package org.thoughtcrime.securesms.util.views;
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import android.util.AttributeSet;
 import android.view.View;
@@ -45,6 +46,7 @@ public class SlideUpWithSnackbarBehavior extends CoordinatorLayout.Behavior<View
     child.setTranslationY(0);
   }
 
+  @SuppressLint("RestrictedApi")
   @Override
   public boolean layoutDependsOn(@NonNull CoordinatorLayout parent,
                                  @NonNull View child,