mail/fetchmail: update to 6.4.19

* CHANGE: fetchmailconf: properly catch and report option parsing errors

* BUG FIX: LMTP: do not try to validate the last component of a
  UNIX-domain LMTP socket as though it were a TCP port.  Reported by
  Christoph Heitkamp, Gitlab issue #33.

* TRANSLATION UPDATE: This fine person has contributed an updated
  translation:
- sr:    Мирослав Николић (Miroslav Nikolić) [Serbian]

PR:		256242
Approved by:	Corey Halpin (maintainer)