Merge pull request #41 from ruby/fix-ci-issue

Lock psych < 5

Author: hsbt

.github/workflows/build.yml

@@ -25,6 +25,6 @@ jobs:
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true
+    - run: gem install rake-compiler
     - name: Run test
-      run: bundle exec rake compile
+      run: rake compile

Gemfile

@@ -7,4 +7,5 @@ group :development do
   gem "rake"
   gem "rake-compiler"
   gem "rdoc"
+  gem "psych", "< 5.0"  # psych 5.0+ requires Ruby 2.7+
 end