Fix Lint/Void offenses

Setter methods return the assigned value. Given:

```rb
class MyClass
  def foo=(v)
    v = 10
    42
  end
end
```

`my_object.foo = 5` will always return `5`

This methods removes code that does not have effect

1 files changed, 0 insertions, 1 deletions

diff --git a/lib/axlsx/workbook/worksheet/pivot_table.rb b/lib/axlsx/workbook/worksheet/pivot_table.rb
index 27065e4b..44a50f19 100644
--- a/lib/axlsx/workbook/worksheet/pivot_table.rb
+++ b/lib/axlsx/workbook/worksheet/pivot_table.rb
@@ -135,7 +135,6 @@ module Axlsx
         end
         @data << data_field
       end
-      @data
     end
 
     # The pages