add Ruby 3.1 and 3.2 to the CI matrix

.github/workflows/checks.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ['2.4', '2.5', '2.6', '2.7', '3.0']
+        ruby: ['2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2']
         rubocop: ['0.63.1', '0.81.0', '0.84.0', '0.85.0', '0.86.0', '0.87.0', '< 1.0', '1.0.0', '1.29.1', '1.30.0', '1.38.0', '< 2.0']
         include:
           - ruby: '2.3'
@@ -36,7 +36,7 @@ jobs:
             rubocop: '1.38.0'
       fail-fast: false
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: use specific rubocop version
       run: echo "gem 'rubocop', '${{ matrix.rubocop }}'" > Gemfile.local
     - name: use specific rubocop-ast version (if required)