Add postpublish script to package.json

package.json

@@ -9,6 +9,7 @@
     "codecov": "nyc --reporter=lcov --reporter=text cucumber-js test",
     "test": "lerna run test"
   },
+  "postpublish" : "PACKAGE_VERSION=$(cat package.json | grep \\\"version\\\" | head -1 | awk -F: '{ print $2 }' | sed 's/[\",]//g' | tr -d '[[:space:]]') && git tag v$PACKAGE_VERSION && git push --tags",
   "workspaces": [
     "packages/api",
     "packages/aws",