Fix Style/SymbolProc offenses

This also provides a performance improvement

```
Comparison (array of 4 elements):
              map(&):  3643131.4 i/s
              map {}:  3488052.5 i/s - 1.04x  (± 0.00) slower

Comparison (array of 20 elements):
              map(&):   466013.9 i/s
              map {}:   408447.2 i/s - 1.14x  (± 0.00) slower
```

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/axlsx/workbook/workbook.rb b/lib/axlsx/workbook/workbook.rb
index ec80d6dc..2c6e0491 100644
--- a/lib/axlsx/workbook/workbook.rb
+++ b/lib/axlsx/workbook/workbook.rb
@@ -171,7 +171,7 @@ module Axlsx
     # @see Comment
     # @return [Comments]
     def comments
-      worksheets.map { |sheet| sheet.comments }.compact
+      worksheets.map(&:comments).compact
     end
 
     # The styles associated with this workbook
@@ -369,7 +369,7 @@ module Axlsx
     # generates a shared string object against all cells in all worksheets.
     # @return [SharedStringTable]
     def shared_strings
-      SharedStringsTable.new(worksheets.collect { |ws| ws.cells }, xml_space)
+      SharedStringsTable.new(worksheets.collect(&:cells), xml_space)
     end
 
     # The xml:space attribute for the worksheet.