[CI] Updates GitHub Actions

Author: picandocodigo

.github/workflows/2.7.yml

@@ -1,4 +1,4 @@
-name: Ruby 2.6
+name: 7x tests
 on:
   push:
     branches:
@@ -16,6 +16,8 @@ jobs:
       RAILS_VERSIONS: '5.0,6.0'
     strategy:
       fail-fast: false
+      matrix:
+        ruby: [ '2.6', '2.7', '3.0' ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
@@ -30,7 +32,7 @@ jobs:
         stack-version: 7.x-SNAPSHOT
     - uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.6
+        ruby-version: ${{ matrix.ruby }}
     - name: Bundle
       run: |
         sudo apt-get install libsqlite3-dev