Add Ruby 2.5.5 to the prebuilt binaries list (#172)

Author: dazuma

Rakefile

@@ -19,10 +19,10 @@ BUNDLER1_VERSION="1.17.3"
 BUNDLER2_VERSION="2.0.1"
 DEFAULT_RUBY_VERSION="2.6.2"
 NODEJS_VERSION="10.15.2"
-GCLOUD_VERSION="237.0.0"
+GCLOUD_VERSION="239.0.0"
 OS_NAME="ubuntu16"
 
-LOCAL_PREBUILT_RUBY_VERSIONS=["2.4.5", "2.5.3", "2.6.2"]
+LOCAL_PREBUILT_RUBY_VERSIONS=["2.4.5", "2.5.5", "2.6.2"]
 LOCAL_PREBUILT_RUBY_IMAGE_BASE="ruby-prebuilt-"
 LOCAL_PREBUILT_RUBY_IMAGE_TAG="latest"
 RELEASED_PREBUILT_RUBY_VERSIONS=::File.readlines("ruby-pipeline/ruby-latest.yaml")

build-ruby-runtime-images.sh

@@ -23,7 +23,7 @@ BASIC_RUBY_VERSION=2.6.2
 BUNDLER1_VERSION=1.17.3
 BUNDLER2_VERSION=2.0.1
 NODEJS_VERSION=10.15.2
-GCLOUD_VERSION=237.0.0
+GCLOUD_VERSION=239.0.0
 
 
 set -e

ruby-pipeline/ruby-latest.yaml

@@ -43,6 +43,7 @@ steps:
            '--prebuilt-image=2.5.1=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.5.1:latest',
            '--prebuilt-image=2.5.3=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.5.3:latest',
            '--prebuilt-image=2.5.4=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.5.4:latest',
+           '--prebuilt-image=2.5.5=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.5.5:latest',
            '--prebuilt-image=2.6.0=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.6.0:latest',
            '--prebuilt-image=2.6.1=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.6.1:latest',
            '--prebuilt-image=2.6.2=gcr.io/gcp-runtimes/ruby/ubuntu16/prebuilt/ruby-2.6.2:latest',