Update httprelayclient.py to force NTLM auth if anonymous auth is enabled (ADCS)

[nobbd]

The httprelayclient has an option where it tries "sending NTLM auth anyways" if the --adcs flag is specified.
The client will however not set the variable self.authenticationMethod and the code will subsequently fail.

If the variable is not set, the following error will occur:

[*] Status code returned: 200. Authentication does not seem required for URL
[-] No authentication requested by the server for url XXX
[*] IIS cert server may allow anonymous authentication, sending NTLM auth anyways
[+] Exception:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/impacket/examples/ntlmrelayx/servers/smbrelayserver.py", line 286, in SmbSessionSetup
    challengeMessage = self.do_ntlm_negotiate(client, token)
  File "/usr/lib/python3/dist-packages/impacket/examples/ntlmrelayx/servers/smbrelayserver.py", line 866, in do_ntlm_negotiate
    return client.sendNegotiate(token)
  File "/usr/lib/python3/dist-packages/impacket/examples/ntlmrelayx/clients/httprelayclient.py", line 83, in sendNegotiate
    serverChallengeBase64 = re.search(('%s ([a-zA-Z0-9+/]+={0,2})' % self.authenticationMethod), res.getheader('WWW-Authenticate')).group(1)
  File "/usr/lib/python3.10/re.py", line 200, in search
    return _compile(pattern, flags).search(string)
TypeError: expected string or bytes-like object

This pull requests sets the self.authenticationMethod to NTLM if the respective branch is executed.

[0xdeaddood]

Thanks @nobbd! Merging...