Use proper "Share to Diaspora" URL

The previous URL leads to an outdated GitHub page that links to websites
which are already available to sale.

This uses the somewhat more official https://share.diasporafoundation.org/

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

apps/federatedfilesharing/templates/settings-personal.php

@@ -31,7 +31,7 @@ style('federatedfilesharing', 'settings-personal');
 			Twitter
 		</button>
 		<button class="social-diaspora pop-up"
-				data-url='https://sharetodiaspora.github.io/?title=<?php p($_['message_without_URL']); ?>&url=<?php p(urlencode($_['reference'])); ?>'>
+				data-url='https://share.diasporafoundation.org/?title=<?php p($_['message_without_URL']); ?>&url=<?php p(urlencode($_['reference'])); ?>'>
 			Diaspora
 		</button>
 		<button id="oca-files-sharing-add-to-your-website">