stdiscosrv has the ability to handle certificates passed by traefik proxy server in X-Forwarded-Tls-Client-Cert header.

Previously, traefik url encodes the content but it stopped doing so since version v2.9.4.
This becomes troublesome for setups where stdiscosrv sits behind newer traefik versions,
as now stdiscosrv tries to url decode the header content when it is not encoded.

The symptom can be very confusing, as if some client's certificate's pem text happens to not contain +, etc, then it works perfectly, but other clients will always fail announcement with 403 error.

More details can be found at traefik/traefik#9669.

I'm not sure what should be the best strategy here to support both old and new traefik versions... but wanted to at least raise attention.

stdiscosrv version: 1.24.0