update dead link to the gpg howto

Fixes: #54


Signed-off-by: Mattia Rizzolo <mattia@debian.org>

templates/notification_mails/newperson.txt

@@ -12,7 +12,7 @@ then visit to make your entry confirmed.
 
 You should not need instructions to decrypt this. If you do not know how to do
 it, you can consider it a challenge. In that case, you can start from here:
-https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html
+https://www.gnupg.org/howtos/en/GPGMiniHowto.html
 
 For any problem, feel free to contact Front Desk at nm@debian.org.
 

[Philippe SWARTVAGHER]

I guess it requires changes in other files as well:

% git grep -Irn https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html
backend/tests/test_email.py:160:https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html
locale/de/LC_MESSAGES/django.po:3136:#| "    href=\"https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html"
locale/de/LC_MESSAGES/django.po:3151:"    href=\"https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html"
public/templates/public/newnm.html:369:    href="https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html">OpenPGP</a>
public/tests/test_newnm.py:154:https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html
templates/notification_mails/newperson.txt:15:https://www.dewinter.com/gnupg_howto/english/GPGMiniHowto.html

[Mattia Rizzolo]

already done a few minutes after that commit 😄