ci: Set up CI with Azure Pipelines (#895)

[skip ci]

Author: KazuCocoa

.azure-pipelines.yml

@@ -0,0 +1,18 @@
+# Ruby
+# Package your Ruby project.
+# Add steps that install rails, analyze code, save build artifacts, deploy, and more:
+# https://docs.microsoft.com/azure/devops/pipelines/languages/ruby
+
+trigger:
+- main
+
+pool:
+  vmImage: 'macOS-10.15'
+
+steps:
+- task: UseRubyVersion@0
+  inputs:
+    versionSpec: '>= 2.6'
+
+- script: bundle install --retry=3 --jobs=4
+  displayName: 'bundle install'