Fix compatibility issue since gem version 0.34.0 google google-cloud-pubsub

[tracyloisel]

Since the 1st of February in 2019, gem google-cloud-pubsub has been updated (0.34.0 version) and it brokes compatibility with this current gem.

Extract from google-cloud-pubsub's changelog, 0.34.0 version :

• Remove the #delay alias for modify_ack_deadline.
  • Users should use the modify_ack_deadline and modify_ack_deadline!
    methods directly instead.

[dibusan]

@ursm When could we expect this PR to be merged and released if at all?
@tracyloisel Is there a workaround I could do? My worker is failing with

ERROR -- : undefined method 'delay!' for #<Google::Cloud::PubSub::ReceivedMessage:0x00560d163808a0> (NoMethodError)
/app/vendor/bundle/ruby/2.4.0/gems/activejob-google_cloud_pubsub-0.7.1/lib/activejob-google_cloud_pubsub/worker.rb:38:in `block (2 levels) in run'

[hkrdrm]

@ursm Any chance this patch can get merged upstream or is this repo pretty much dead in the water. I've playing with @tracyloisel fork and couple others but seems like I'm going to just have to fork and pull in patches from all the other forks. If this repo is dead do we have anyone willing to takeover and maintain it.