Fix dockerfile by using a pinned release for Caddy (old dl URL change…

…d, latest release has a regression on 'without' for the proxy directive).

Signed-off-by: Marios Andreopoulos <opensource@andmarios.com>

docker/Dockerfile

@@ -7,10 +7,10 @@ RUN apk add --no-cache ca-certificates wget \
     && echo "progress = dot:giga" | tee /etc/wgetrc
 
 # Add and Setup Caddy webserver
-RUN wget "https://caddyserver.com/download/build?os=linux&arch=amd64&features=" \
-         -O /caddy.tgz \
+RUN wget "https://github.com/mholt/caddy/releases/download/v0.9.5/caddy_linux_amd64.tar.gz" -O /caddy.tgz \
     && mkdir caddy \
     && tar xzf caddy.tgz -C /caddy \
+    && mv /caddy/caddy_linux_amd64 /caddy/caddy \
     && rm -f /caddy.tgz
 
 # Add and Setup Schema-Registry-Ui