Continue fleshing out post-release job

Forgot to actually add changes to the commit. Do it now.

concourse/tasks/bump-package-json-versions.sh

@@ -12,6 +12,7 @@ do
     cd $sources/$extension_id
     echo "Should update version of $extension_id to $version"
     npm version $version
+    git add package.json
     echo ""
 done