Merge pull request msgpack#178 from francesco-loreti/msgpack#177

msgpack#177 Added support for Ruby-2.7

Author: tagomoris

Rakefile

@@ -69,7 +69,7 @@ namespace :build do
   task :windows do
     require 'rake_compiler_dock'
     # See RUBY_CC_VERSION in https://github.com/rake-compiler/rake-compiler-dock/blob/master/Dockerfile
-    RakeCompilerDock.sh 'bundle && gem i json && rake cross native gem RUBY_CC_VERSION=2.2.2:2.3.0:2.4.0:2.5.0:2.6.0'
+    RakeCompilerDock.sh 'bundle && gem i json && rake cross native gem RUBY_CC_VERSION=2.2.2:2.3.0:2.4.0:2.5.0:2.6.0:2.7.0'
   end
 end