Dropped your co-maint on Mail::Sendmail

[Neil Bowers]

Hi Abe,

As per the discussion on this ticket, I have just dropped your co-maint on 
Mail::Sendmail, which was causing some indexing confusion, both for PAUSE and 
MetaCPAN:

        https://github.com/metacpan/metacpan-api/issues/811

Cheers,
Neil