cf: use fallback URL for curseforge files like modpack files (#3158)

Author: itzg

Dockerfile

@@ -50,7 +50,7 @@ RUN easy-add --var os=${TARGETOS} --var arch=${TARGETARCH}${TARGETVARIANT} \
   --var version=${MC_SERVER_RUNNER_VERSION} --var app=mc-server-runner --file {{.app}} \
   --from ${GITHUB_BASEURL}/itzg/{{.app}}/releases/download/{{.version}}/{{.app}}_{{.version}}_{{.os}}_{{.arch}}.tar.gz
 
-ARG MC_HELPER_VERSION=1.40.4
+ARG MC_HELPER_VERSION=1.40.6
 ARG MC_HELPER_BASE_URL=${GITHUB_BASEURL}/itzg/mc-image-helper/releases/download/${MC_HELPER_VERSION}
 # used for cache busting local copy of mc-image-helper
 ARG MC_HELPER_REV=1