Fix hash transformation related offenses

- Style/HashConversion
- Style/HashTransformKeys

```
Comparison (IPS):
      transform_keys:  2890030.0 i/s
           Hash[map]:  1777641.0 i/s - 1.63x  (± 0.00) slower

Comparison (Memory):
      transform_keys:        168 allocated
           Hash[map]:        248 allocated - 1.48x more
```

3 files changed, 2 insertions, 15 deletions

diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 19c4b3f5..20efee78 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -223,13 +223,6 @@ Style/GuardClause:
     - 'lib/axlsx/workbook/worksheet/table.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowSplatArgument.
-Style/HashConversion:
-  Exclude:
-    - 'lib/axlsx/workbook/worksheet/cell_serializer.rb'
-    - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: AllowedReceivers.
 # AllowedReceivers: Thread.current
@@ -244,12 +237,6 @@ Style/HashEachMethods:
 Style/HashSyntax:
   Enabled: false
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-Style/HashTransformKeys:
-  Exclude:
-    - 'lib/axlsx/workbook/worksheet/cell_serializer.rb'
-    - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
-
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: AllowIfModifier.
 Style/IfInsideElse:
diff --git a/lib/axlsx/workbook/worksheet/cell_serializer.rb b/lib/axlsx/workbook/worksheet/cell_serializer.rb
index f45d3c73..dceca7eb 100644
--- a/lib/axlsx/workbook/worksheet/cell_serializer.rb
+++ b/lib/axlsx/workbook/worksheet/cell_serializer.rb
@@ -26,7 +26,7 @@ module Axlsx
       def run_xml_string(cell, str = +'')
         if cell.is_text_run?
           valid = RichTextRun::INLINE_STYLES - [:value, :type]
-          data = Hash[Axlsx.instance_values_for(cell).map { |k, v| [k.to_sym, v] }]
+          data = Axlsx.instance_values_for(cell).transform_keys(&:to_sym)
           data = data.select { |key, value| valid.include?(key) && !value.nil? }
           RichText.new(cell.value.to_s, data).to_xml_string(str)
         elsif cell.contains_rich_text?
diff --git a/lib/axlsx/workbook/worksheet/rich_text_run.rb b/lib/axlsx/workbook/worksheet/rich_text_run.rb
index 883d01d3..ffd2f941 100644
--- a/lib/axlsx/workbook/worksheet/rich_text_run.rb
+++ b/lib/axlsx/workbook/worksheet/rich_text_run.rb
@@ -207,7 +207,7 @@ module Axlsx
     # @return [String]
     def to_xml_string(str = +'')
       valid = RichTextRun::INLINE_STYLES
-      data = Hash[Axlsx.instance_values_for(self).map { |k, v| [k.to_sym, v] }]
+      data = Axlsx.instance_values_for(self).transform_keys(&:to_sym)
       data = data.select { |key, value| valid.include?(key) && !value.nil? }
 
       str << '<r><rPr>'