Use Ruby 2.6 to run rubocop

.

Author: byroot

.github/workflows/test.yaml

@@ -18,7 +18,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "2.5"
+          ruby-version: "2.6"
       - name: Set up Gems
         run: |
           gem update --system --no-document