[ruby/securerandom] Only define compatible method in < Ruby 3.3

ruby/securerandom@2c8cdfba7b

Author: hsbt

lib/securerandom.rb

@@ -53,13 +53,9 @@ def bytes(n)
 
     # Compatibility methods for Ruby 3.2, we can remove this after dropping to support Ruby 3.2
     def alphanumeric(n = nil, chars: ALPHANUMERIC)
-      if RUBY_VERSION < '3.3'
-        n = 16 if n.nil?
-        choose(chars, n)
-      else
-        super n, chars: chars
-      end
-    end
+      n = 16 if n.nil?
+      choose(chars, n)
+    end if RUBY_VERSION < '3.3'
 
     private