server/email_notifications: do not double html escape

the default escape handler is handlebars::html_escape, but this are
plain text emails and we manually escape them for the html part, so
set the default escape handler to 'no_escape'

this avoids double html escape for the characters: '&"<>' in emails

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/server/email_notifications.rs

@@ -185,6 +185,7 @@ lazy_static::lazy_static!{
         let result: Result<(), TemplateError> = try_block!({
 
             hb.set_strict_mode(true);
+            hb.register_escape_fn(handlebars::no_escape);
 
             hb.register_helper("human-bytes", Box::new(handlebars_humam_bytes_helper));
             hb.register_helper("relative-percentage", Box::new(handlebars_relative_percentage_helper));