Run bundle update too, print exit code

This modifies the update script so that it explicitly runs 'bundle
update' in addition to 'bundle install' and makes the last step to be
printing of the exit code.

Author: genebean

docker/test-all-providers/update-gemfile-lock.sh

@@ -3,4 +3,4 @@
 docker run -it --rm \
   -v $(pwd):/app \
   $(grep ^FROM ./Dockerfile |cut -d ' ' -f2) \
-  /bin/bash -c 'apt-get update -qq && apt-get install -y --no-install-recommends make && cd /app && gem install bundler && bundle install --jobs 3'
+  /bin/bash -c 'apt-get update -qq && apt-get install -y --no-install-recommends make && cd /app && gem install bundler && bundle install --jobs 3 && bundle update; echo "LOCK_FILE_UPDATE_EXIT_CODE=$?"'