Ensure that network is up when rspamd is started

otherwise, it can fail to reach remote rspamd hosts

Index: rspamd-2.6/rspamd.service
===================================================================
--- rspamd-2.6.orig/rspamd.service
+++ rspamd-2.6/rspamd.service
@@ -1,6 +1,7 @@
 [Unit]
 Description=rapid spam filtering system
-After=nss-lookup.target network-online.target
+After=nss-lookup.target network-online.target redis.target
+Wants=network-online.target
 Documentation=https://rspamd.com/doc/
 
 [Service]