fix: Add a periodic update of dynamic probes

We add in our HTTP probes some keywords. Recompute them on a regular
basis to take account of service updates.

Closes #5

nixos/module.nix

@@ -80,6 +80,8 @@ in
 
       wantedBy = [ "multi-user.target" ];
 
+      startAt = "daily";
+
       script = ''
         UPTIME_KUMA_PASSWORD=$(cat $CREDENTIALS_DIRECTORY/password) ${lib.getExe config.statelessUptimeKuma.build.script}
       '';