letsencrypt: Replace a Unicode char with ASCII
letsencrypt: Replace a Unicode char with ASCII

Although there is nothing wrong with the generated POT file and the
encoding is properly set to UTF-8, Weblate failed with following error:

We have not been able to update the source file for the resource
django.pot of the project FreedomBox UI.

The URL we used to update the source file from was
https://raw.githubusercontent.com/freedombox/Plinth/master/plinth/locale/django.pot.

The exact error we encountered was:

'ascii' codec can't encode character u'\u2019' in position 31271:
ordinal not in range(128)

kkampardi/Plinth,vignanl/Plinth,harry-7/Plinth,kkampardi/Plinth,freedomboxtwh/Plinth,freedomboxtwh/Plinth,kkampardi/Plinth,freedomboxtwh/Plinth,freedomboxtwh/Plinth,kkampardi/Plinth,kkampardi/Plinth,harry-7/Plinth,vignanl/Plinth,harry-7/Plinth,freedomboxtwh/Plinth,vignanl/Plinth,harry-7/Plinth,vignanl/Plinth,harry-7/Plinth,vignanl/Plinth