update nodejs:6 runtime to 6.11.4
diff --git a/core/nodejs6Action/Dockerfile b/core/nodejs6Action/Dockerfile
index 347ea00..73cd413 100644
--- a/core/nodejs6Action/Dockerfile
+++ b/core/nodejs6Action/Dockerfile
@@ -1,7 +1,7 @@
FROM nodejsactionbase
# based on https://github.com/nodejs/docker-node
-ENV NODE_VERSION 6.9.1
+ENV NODE_VERSION 6.11.4
RUN curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz" \
&& tar -xzf "node-v$NODE_VERSION-linux-x64.tar.gz" -C /usr/local --strip-components=1 \
&& rm "node-v$NODE_VERSION-linux-x64.tar.gz"