Fix the rake spec failures under ruby 2.4.

Ths typo3_spec is giving some errors under ruby 2.4+
and OpenSSL 1.1+.

lib/msf/core/exploit/http/typo3/login.rb

@@ -100,8 +100,13 @@ module Msf::Exploit::Remote::HTTP::Typo3::Login
     key = OpenSSL::PKey::RSA.new
     exponent = OpenSSL::BN.new e.hex.to_s
     modulus = OpenSSL::BN.new n.hex.to_s
+    if key.respond_to?(:set_key)
+      # Ruby 2.4+
+      key.set_key(modulus, exponent, nil)
+    else
       key.e = exponent
       key.n = modulus
+    end
     enc = key.public_encrypt(password)
     enc_b64 = Rex::Text.encode_base64(enc)
     "rsa:#{enc_b64}"