Update bundler version

[dombarnes]

The currently included version of Bundler is 1.13.6 which was released in October 2016. v2 has now been released as of January 2019, and v1.13.6 does not work with a v2 created Gemfile.lock

[uberllama]

Bumping this given the importance of the issue.

[GisliGeorgs]

Bumping as I'm running into this.
Also, the newest Ruby version available in App Services was released in March of 2019.

[amsimon]

Bumping this. Is this repo being maintained?

[thr-eki]

Up. The current bundler version makes my build crash.

I miss libruby.so required by the BSON gem.

If I manually force to install bundler 1.17.3 for example it works, but I have to bunde install everytime and takes forever to restart or redeploy anything.

Hello! Any updates?