Fix Style/HashEachMethods offense

Replace `keys.each` with hash iteration

```rb
MY_HASH = {
  first: '1',
  second: '2',
  third: '3'
}

%i[ips memory].each do |benchmark|
  Benchmark.send(benchmark) do |x|
    x.report("each_key") { MY_HASH.each_key { |k| MY_HASH[k] } }
    x.report("keys.each") { MY_HASH.keys.each { |k| MY_HASH[k] } }
    x.report("each") { MY_HASH.each { |k, v| v } }
    x.compare!
  end
end
```

```
IPS Comparison:
                each:  4283031.6 i/s
            each_key:  3683407.4 i/s - 1.16x  (± 0.00) slower
           keys.each:  3387425.1 i/s - 1.26x  (± 0.00) slower

Memory Comparison:
            each_key:          0 allocated
                each:          0 allocated - same
           keys.each:         40 allocated - Infx more
```

1 files changed, 0 insertions, 7 deletions

diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index bb6a38f9..4aaaa2ed 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -183,13 +183,6 @@ Style/GuardClause:
     - 'lib/axlsx/workbook/worksheet/table.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: AllowedReceivers.
-# AllowedReceivers: Thread.current
-Style/HashEachMethods:
-  Exclude:
-    - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
-
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: AllowIfModifier.
 Style/IfInsideElse: