Update Dockerfile

Dockerfile

@@ -1,10 +1,10 @@
-ARG CADDY_VERSION
-FROM caddy:${CADDY_VERSION}-builder AS builder
-ARG CADDY_DOCKER_PROXY_VERSION
+ARG WEBSERVER_VERSION
+FROM caddy:${WEBSERVER_VERSION}-builder AS builder
+ARG DOCKER_PROXY_VERSION
 RUN xcaddy build \
-    --with github.com/lucaslorentz/caddy-docker-proxy/v2@v${CADDY_DOCKER_PROXY_VERSION} \
+    --with github.com/lucaslorentz/caddy-docker-proxy/v2@v${DOCKER_PROXY_VERSION} \
     --with github.com/caddy-dns/ovh
 
-FROM caddy:${CADDY_VERSION}-alpine
+FROM caddy:${WEBSERVER_VERSION}-alpine
 COPY --from=builder /usr/bin/caddy /usr/bin/caddy
 CMD ["caddy", "docker-proxy"]