fixes #1723: Github Actions Supported (#1729)

* fixes #1723: Github Actions Supported

- This is to switch from Travis CI which is shutting down the org version,
  and the .com version, a free account is limited.
- Switch test environment variable from TRAVIS to CI to be more generic.

* Adding jruby-9.2.18.0 to matrix for github actions

test/test_migrate.rb

@@ -44,7 +44,7 @@ def load_script(**args)
   end  
 end
 
-unless ENV['TRAVIS']
+unless ENV['CI']
 
   context '4.x -> 5.x tag migrator' do
     include Rack::Test::Methods