[CI] Adds Ruby 3 to CI

Author: picandocodigo

.ci/test-matrix.yml

@@ -3,6 +3,7 @@ STACK_VERSION:
   - 7.12.0-SNAPSHOT
 
 RUBY_TEST_VERSION:
+- 3.0
 - 2.7
 - 2.6
 - 2.5

.github/workflows/7.12.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ 2.5, 2.6, 2.7, jruby-9.2 ]
+        ruby: [ 2.5, 2.6, 2.7, 3.0, jruby-9.2 ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2