fix(docker): correct GitHub release asset URL for server zip download

Author: masterking32

docker/Dockerfile

@@ -32,7 +32,7 @@ RUN set -eux; \
   esac; \
   curl -fsSL --retry 3 --retry-delay 2 \
   -o /tmp/masterdnsvpn.zip \
-  "https://github.com/masterking32/MasterDnsVPN/releases/${RELEASE_TAG}/download/${ARTIFACT}"; \
+  "https://github.com/masterking32/MasterDnsVPN/releases/download/${RELEASE_TAG}/${ARTIFACT}"; \
   if [ -n "${RELEASE_SHA256}" ]; then \
   echo "${RELEASE_SHA256}  /tmp/masterdnsvpn.zip" | sha256sum -c -; \
   fi; \