Log Message:
fetchmail: Update to 6.4.15

upstream changes:
-----------------
fetchmail-6.4.15 (released 2021-01-03, 27614 LoC):
# BUG FIXES
* Fix a typo in the manual page reported by David McKelvie.
* Fix cross-compilation with openssl, by Fabrice Fontaine. Merge request !23.
* Fix truncation of SMTP PLAIN AUTH with ^ in credentials, by Earl Chew.   \ 
Gitlab issue #23, merge request !25.

fetchmail-6.4.14 (released 2020-11-26, 27608 LoC):
# TRANSLATION UPDATES were made by these fine people:
* sr:    Мирослав Николић (Miroslav Nikolić) [Serbian]