nixos/taskserver: Constrain server cert perms

It doesn't do much harm to make the server certificate world readable,
because even though it's not accessible anymore via the file system,
someone can still get it by simply doing a TLS handshake with the
server.

So this is solely for consistency.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

nixos/modules/services/misc/taskserver/default.nix

@@ -388,9 +388,13 @@ in {
             --load-privkey "${cfg.dataDir}/keys/server.key" \
             --outfile "${cfg.dataDir}/keys/server.cert"
 
-          chgrp "${cfg.group}" "${cfg.dataDir}/keys/server.key"
-          chmod g+r "${cfg.dataDir}/keys/server.key"
-          chmod a+r "${cfg.dataDir}/keys/server.cert"
+          chgrp "${cfg.group}" \
+            "${cfg.dataDir}/keys/server.key" \
+            "${cfg.dataDir}/keys/server.cert"
+
+          chmod g+r \
+            "${cfg.dataDir}/keys/server.key" \
+            "${cfg.dataDir}/keys/server.cert"
         fi
 
         chmod go+x "${cfg.dataDir}/keys"