[PATCH proxmox-acme v2] acme: fix USER_AGENT variable interpolation in curl calls

[Aaron Carson <aaron@aaroncarson.co.uk>]

The variable was not interpolated, so ACME requests were sent with
the literal string USER_AGENT as the user agent instead of the
configured value.

Signed-off-by: Aaron Carson <aaron@aaroncarson.co.uk>
---
Hi folks, resending with the correct subject prefix (v1 went out as
[PATCH acme]). Noticed the user agent my DNS server was seeing when
updating records for ACME was literally the string USER_AGENT - the
variable isn't interpolated in the two _get_impl curl calls. My CLA
is on file (office@ responded on 6th Aug).

v2: correcting subject prefix, no code changes

 src/proxmox-acme | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/proxmox-acme b/src/proxmox-acme
index 705f7df..39c770b 100644
--- a/src/proxmox-acme
+++ b/src/proxmox-acme
@@ -348,9 +348,9 @@ _get_impl() {
     _CURL="$_CURL --connect-timeout $t"
   fi
   if [ "$onlyheader" ]; then
-    $_CURL -I --user-agent "USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" -H "$_H5" "$url"
+    $_CURL -I --user-agent "$USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" -H "$_H5" "$url"
   else
-    $_CURL --user-agent "USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" -H "$_H5" "$url"
+    $_CURL --user-agent "$USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" -H "$_H5" "$url"
   fi
   ret=$?
   if [ "$ret" != "0" ]; then
-- 
2.52.0