Add link to funding page rather than checkout

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/html/about.html

@@ -22,7 +22,7 @@
 
 </div>
 <div class="panel-footer">
-<a class="btn btn-default" href="https://salt.bountysource.com/checkout/amount?team=weblate">{% trans "Fund Weblate!" %}</a>
+<a class="btn btn-default" href="https://salt.bountysource.com/teams/weblate">{% trans "Fund Weblate!" %}</a>
 <a class="btn btn-primary" href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=AXN88S8GX5MQ4"><i class="fa fa-paypal"></i> {% trans "Donate to Weblate!" %}</a>
 </div>
 </div>