Restore SecureRandom.alphanumeric same as Random::Formatter.alphanumeric of Ruby 3.3/3.4

Fixes #35

Author: hsbt

lib/securerandom.rb

@@ -51,6 +51,16 @@ def bytes(n)
       return gen_random(n)
     end
 
+    # 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
+
     private
 
     # :stopdoc:

test/test_securerandom.rb

@@ -9,6 +9,12 @@ def setup
     @it = SecureRandom
   end
 
+  def test_alphanumeric_with_chars
+    assert_nothing_raised(ArgumentError) do
+      @it.alphanumeric(1, chars: ("0".."9").to_a)
+    end
+  end
+
   # This test took 2 minutes on my machine.
   # And 65536 times loop could not be enough for forcing PID recycle.
   # TODO: We should run this test only on GitHub Actions.