Conditionally check alphanumeric method parameters

In ruby/securerandom#34, Random::Formatter was
removed from securerandom. This change broke the alphanumeric method
signature in Ruby 3.2 since the `chars` parameter isn't available
there yet.

activesupport/lib/active_support/core_ext/securerandom.rb

@@ -16,8 +16,18 @@ module SecureRandom
   #
   #   p SecureRandom.base58 # => "4kUgL2pdQMSCQtjE"
   #   p SecureRandom.base58(24) # => "77TMHrHJFvFDwodq8w7Ev2m7"
-  def self.base58(n = 16)
-    alphanumeric(n, chars: BASE58_ALPHABET)
+  if SecureRandom.method(:alphanumeric).parameters.size == 2 # Remove check when Ruby 3.3 is the minimum supported version
+    def self.base58(n = 16)
+      alphanumeric(n, chars: BASE58_ALPHABET)
+    end
+  else
+    def self.base58(n = 16)
+      SecureRandom.random_bytes(n).unpack("C*").map do |byte|
+        idx = byte % 64
+        idx = SecureRandom.random_number(58) if idx >= 58
+        BASE58_ALPHABET[idx]
+      end.join
+    end
   end
 
   # SecureRandom.base36 generates a random base36 string in lowercase.
@@ -31,7 +41,17 @@ def self.base58(n = 16)
   #
   #   p SecureRandom.base36 # => "4kugl2pdqmscqtje"
   #   p SecureRandom.base36(24) # => "77tmhrhjfvfdwodq8w7ev2m7"
-  def self.base36(n = 16)
-    alphanumeric(n, chars: BASE36_ALPHABET)
+  if SecureRandom.method(:alphanumeric).parameters.size == 2 # Remove check when Ruby 3.3 is the minimum supported version
+    def self.base36(n = 16)
+      alphanumeric(n, chars: BASE36_ALPHABET)
+    end
+  else
+    def self.base36(n = 16)
+      SecureRandom.random_bytes(n).unpack("C*").map do |byte|
+        idx = byte % 64
+        idx = SecureRandom.random_number(36) if idx >= 36
+        BASE36_ALPHABET[idx]
+      end.join
+    end
   end
 end