Rubocop fixed: Style/FormatString

.rubocop.yml

@@ -64,11 +64,6 @@ Style/FileName:
   - tests/ycp/InRuby.rb
   - tests/ycp/URI.rb
 
-# Offense count: 3
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-Style/FormatString:
-  Enabled: false
-
 # Offense count: 3
 # Configuration parameters: MinBodyLength.
 Style/GuardClause:

src/ruby/yast/builtins.rb

@@ -856,14 +856,14 @@ def self.tohexstring(int, width = 0)
       return nil if int.nil? || width.nil?
 
       if int >= 0
-        sprintf("0x%0#{width}x", int)
+        format("0x%0#{width}x", int)
       else
         # compatibility for negative numbers
         # Ruby: -3 => '0x..fd'
         # Yast:  -3 => '0xfffffffffffffffd' (64bit integer)
 
         # this has '..fff' prefix
-        ret = sprintf("%018x", int)
+        ret = format("%018x", int)
 
         # pad with zeroes or spaces if needed
         if width > 16
@@ -892,7 +892,7 @@ def self.tostring(val, width = nil)
       if width
         raise "tostring: negative 'width' argument: #{width}" if width < 0
 
-        return "%.#{width}f" % val
+        return format("%.#{width}f", val)
       end
 
       case val