Update the bundler version to the latest version before running the CI.

Author: postmodern

Diff for: .github/workflows/ruby.yml

@@ -23,6 +23,7 @@ jobs:
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
+          bundler: latest
       - name: Install dependencies
         run: |
           sudo apt update -y && \