add quotes to resolve shell check failure

dnsapi/dns_edgedns.sh

@@ -444,7 +444,7 @@ _edgedns_base64_hmac_sha256() {
   _secure_debug2 "encoded key" "$encoded_key"
 
   encoded_key_hex=$(printf "%s" "$encoded_key" | _hex_dump | tr -d ' ')
-  data_sig="$(echo "$encoded_data" | tr -d "\n\r" | _hmac sha256 $encoded_key_hex | _base64)"
+  data_sig="$(echo "$encoded_data" | tr -d "\n\r" | _hmac sha256 "$encoded_key_hex" | _base64)"
 
   _secure_debug2 "data_sig:" "$data_sig"
   _hmac_out="$(echo "$data_sig" | tr -d "\n\r" | iconv -f utf-8)"