Bump vmpooler requirement and add install gemfile script

Gemfile.lock

@@ -4,7 +4,7 @@ PATH
     vmpooler-dns-gcp (0.1.0)
       google-cloud-dns (~> 0.35.1)
       googleauth (>= 0.16.2, < 1.3.0)
-      vmpooler (~> 2.3, >= 1.3.0)
+      vmpooler (~> 3.0)
 
 GEM
   remote: https://rubygems.org/
@@ -172,7 +172,7 @@ GEM
     trailblazer-option (0.1.2)
     uber (0.1.0)
     unicode-display_width (1.8.0)
-    vmpooler (2.4.0)
+    vmpooler (3.0.0)
       concurrent-ruby (~> 1.1)
       connection_pool (~> 2.2)
       deep_merge (~> 1.2)

install-gemfile-lock

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+# The container tag should closely match what is used in `docker/Dockerfile` in vmpooler-deployment
+docker run -it --rm \
+  -v $(pwd):/app \
+  jruby:9.4.1.0-jdk11 \
+  /bin/bash -c 'apt-get update -qq && apt-get install -y --no-install-recommends make git netbase && cd /app && gem install bundler && bundle install --jobs 3; echo "LOCK_FILE_UPDATE_EXIT_CODE=$?"'

vmpooler-dns-gcp.gemspec

@@ -22,7 +22,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
   spec.add_dependency "googleauth", ">= 0.16.2", "< 1.3.0"
   spec.add_dependency "google-cloud-dns", "~> 0.35.1"
-  spec.add_dependency 'vmpooler', '>= 1.3.0', '~> 2.3'
+  spec.add_dependency 'vmpooler', '~> 3.0'
 
   # Testing dependencies
   spec.add_development_dependency 'mock_redis', '>= 0.17.0'