Release google-auth-library-ruby 0.10.0 (#240)
Release google-auth-library-ruby 0.10.0 (#240)

Note: This release now requires Ruby 2.4 or later

* Increase metadata timeout to improve reliability in some hosting environments
* Support an environment variable to suppress Cloud SDK credentials warnings
* Make the header check case insensitive
* Set instance variables at initialization to avoid spamming warnings
* Pass "Metadata-Flavor" header to metadata server when checking for GCE

googleapis/google-auth-library-ruby,googleapis/google-auth-library-ruby