Update RBI files for logger.

Autogenerated by the [vendor-gems](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/vendor-gems.yml) workflow.

Library/Homebrew/sorbet/rbi/gems/logger@1.6.2.rbi

@@ -770,12 +770,15 @@ class Logger
 
   private
 
-  # source://logger//lib/logger.rb#754
+  # source://logger//lib/logger.rb#758
   def format_message(severity, datetime, progname, msg); end
 
   # source://logger//lib/logger.rb#745
   def format_severity(severity); end
 
+  # source://logger//lib/logger.rb#754
+  def level_key; end
+
   # Guarantee the existence of this ivar even when subclasses don't call the superclass constructor.
   #
   # source://logger//lib/logger.rb#750