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

.github/workflows/test.yaml

@@ -0,0 +1,29 @@
+name: Ruby Build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: [2.4.0, 2.6.0, 3.0.0, jruby-9.2.18.0]
+    steps:
+      - run: echo "The job was automatically triggered by a ${{ github.event_name }} event."
+      - run: echo "This job is now running on a ${{ runner.os }} server hosted by GitHub!"
+      - run: echo "The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
+      - name: Check out repository code
+        uses: actions/checkout@v2
+      - run: echo "The ${{ github.repository }} repository has been cloned to the runner."
+      - run: echo "The workflow is now ready to test your code on the runner."
+      - name: List files in the repository
+        run: |
+          ls ${{ github.workspace }}
+      - uses: actions/setup-java@v2
+        with:
+          distribution: 'adopt'
+          java-version: '9'
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: exec rake
+        run: bundle exec rake