[PATCH proxmox-acme] fix: acme: add missing `_json_decode` function

[Shan Shaji <s.shaji@proxmox.com>]

While placing the ACME certificate order using the Active24 plugin,
the request was failing [0]. This was because, `_json_decode` function
was referenced inside the dns_active24.sh file but was never defined
in the `proxmox-acme` script.To fix it, the missing function was added
by referencing the implementation from the acme.sh [1] script.

- [0] https://forum.proxmox.com/threads/acme-active24-dns-plugin-error-json_decode-command-not-found.182899/
- [1] https://github.com/acmesh-official/acme.sh/blob/master/acme.sh#L912

Signed-off-by: Shan Shaji <s.shaji@proxmox.com>
---

 **note**: I couldn't test the changes as i don't have Active24 credentials.
 
 src/proxmox-acme | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/proxmox-acme b/src/proxmox-acme
index 9eea590..499d533 100644
--- a/src/proxmox-acme
+++ b/src/proxmox-acme
@@ -913,6 +913,14 @@ _source_plugin_config() {
   return 0
 }
 
+# from: http:\/\/ to http://
+_json_decode() {
+  _j_str="$(sed 's#\\/#/#g')"
+  _debug3 "_json_decode"
+  _debug3 "_j_str" "$_j_str"
+  echo "$_j_str"
+}
+
 # Proxmox implementation to inject the DNSAPI variables
 _load_plugin_config() {
     while IFS= read -r line; do
-- 
2.47.3