Fix conf base for child domains

[lefayjey]

Hello, I had an issue while running the tool against ADCS on a child domain. This fix is working for me (on child and parent domains). Please find details below.

└─$ certi.py list north.sevenkingdoms.local/hodor:hodor --dc-ip 192.168.56.11             
Traceback (most recent call last):
  File "/home/kali/.local/bin/certi.py", line 8, in <module>
    sys.exit(main())
  File "/home/kali/.local/pipx/venvs/certi/lib/python3.10/site-packages/certilib/main.py", line 245, in main
    return main_list(args)
  File "/home/kali/.local/pipx/venvs/certi/lib/python3.10/site-packages/certilib/main.py", line 450, in main_list
    templates = list(fetch_templates(
  File "/home/kali/.local/pipx/venvs/certi/lib/python3.10/site-packages/certilib/main.py", line 651, in fetch_templates
    resp = search_ldap(
  File "/home/kali/.local/pipx/venvs/certi/lib/python3.10/site-packages/certilib/ldap.py", line 69, in search_ldap
    return ldap_conn.search(
  File "/home/kali/.local/pipx/venvs/certi/lib/python3.10/site-packages/impacket/ldap/ldap.py", line 350, in search
    raise LDAPSearchError(
impacket.ldap.ldap.LDAPSearchError: Error in searchRequest -> noSuchObject: 0000208D: NameErr: DSID-0310028C, problem 2001 (NO_OBJECT), data 0, best match of:
        'DC=north,DC=sevenkingdoms,DC=local'

The error is caused by the config base conf_base = "CN=Configuration,{}".format(get_base_dn(domain)), which should be containing the root domain and not the full child domain:

Thanks!