Update plugin.sh

plugin.sh

@@ -60,6 +60,10 @@ if [ -n "${PLUGIN_BUILD_ARGS_FROM_ENV:-}" ]; then
     BUILD_ARGS_FROM_ENV=$(echo "${PLUGIN_BUILD_ARGS_FROM_ENV}" | tr ',' '\n' | while read build_arg; do echo "--build-arg ${build_arg}=$(eval "echo \$$build_arg")"; done)
 fi
 
+if [[ "${PLUGIN_SKIP_UNUSED_STAGES:-}" == "true" ]]; then
+    SKIP_UNUSED_STAGES="--skip-unused-stages=true"
+fi
+
 # auto_tag, if set auto_tag: true, auto generate .tags file
 # support format Major.Minor.Release or start with `v`
 # docker tags: Major, Major.Minor, Major.Minor.Release and latest
@@ -107,5 +111,7 @@ fi
     ${CACHE_TTL:-} \
     ${CACHE_REPO:-} \
     ${TARGET:-} \
+    ${SKIP_UNUSED_STAGES:-} \
     ${BUILD_ARGS:-} \
-    ${BUILD_ARGS_FROM_ENV:-}
+    ${BUILD_ARGS_FROM_ENV:-}
+