Update UI test

Author: bluebear94

tests/ui/default_box_assignments.fixed

@@ -1,12 +1,12 @@
 #![warn(clippy::default_box_assignments)]
 
 fn with_default<T: Default>(b: &mut Box<T>) {
-    *(*b) = T::default();
+    **b = T::default();
     //~^ default_box_assignments
 }
 
 fn with_sized<T>(b: &mut Box<T>, t: T) {
-    *(*b) = t;
+    **b = t;
     //~^ default_box_assignments
 }
 

tests/ui/default_box_assignments.stderr

@@ -2,7 +2,7 @@ error: creating a new box
   --> tests/ui/default_box_assignments.rs:4:5
    |
 LL |     *b = Box::new(T::default());
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace existing content with inner value instead: `*(*b) = T::default()`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace existing content with inner value instead: `**b = T::default()`
    |
    = note: this creates a needless allocation
    = note: `-D clippy::default-box-assignments` implied by `-D warnings`
@@ -12,7 +12,7 @@ error: creating a new box
   --> tests/ui/default_box_assignments.rs:9:5
    |
 LL |     *b = Box::new(t);
-   |     ^^^^^^^^^^^^^^^^ help: replace existing content with inner value instead: `*(*b) = t`
+   |     ^^^^^^^^^^^^^^^^ help: replace existing content with inner value instead: `**b = t`
    |
    = note: this creates a needless allocation