update github workflow to run cfn-nag

Author: ievgeniia ieromenko

.github/workflows/cfn-nag.yml

@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - name: Set up Ruby 2.6
+      - name: Set up Ruby 2.7
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '2.6'
+          ruby-version: '2.7'
       - name: Install cfn-nag
         run: gem install cfn-nag
       - name: Scan files in all templates folders