fix(hetzner): opening rules file will give structured data since its .json

firewall/provider/hetzner/app.nu

···
 log info $"backing up firewall ($firewallId) to ($backupPath)"
 
 # apply rules
-let resp = open $rulesFile | from json | post $"/firewalls/($firewallId)/actions/set_rules"
+let resp = open $rulesFile | post $"/firewalls/($firewallId)/actions/set_rules"
 if $resp.status != 201 {
   log error $"could not apply firewall \(id ($firewallId)\)"
 }