need logger for exifr

Author: toy

Gemfile

@@ -4,6 +4,10 @@ source 'https://rubygems.org'
 
 gemspec
 
+if RUBY_VERSION >= '4'
+  gem 'logger'
+end
+
 if ENV['CC_TEST_REPORTER_ID']
   group :test do
     gem 'simplecov'