Fix applying DES-CBC when using OpenSSL 3

After calling `#final` on the cipher object, it will return garbage from
that moment forward. The cipher object can therefore not be reused in
the iteration over keys. Reinitialize it everytime instead.

This seems to be new behaviour in Ruby/OpenSSL3. See also:
https://ruby.github.io/openssl/OpenSSL/Cipher.html#class-OpenSSL::Cipher-label-Calling+Cipher-23final

lib/net/ntlm.rb

@@ -123,9 +123,9 @@ def gen_keys(str)
       end
 
       def apply_des(plain, keys)
-        dec = OpenSSL::Cipher.new("des-cbc").encrypt
-        dec.padding = 0
         keys.map {|k|
+          dec = OpenSSL::Cipher.new("des-cbc").encrypt
+          dec.padding = 0
           dec.key = k
           dec.update(plain) + dec.final
         }