ci: Use "latest" Bundler with Ruby "head"

Prevents picking up of the Gemfile's v2.4.22 which is no longer compatible with
Ruby 4.

Author: tokengeek

.github/workflows/ruby.yml

@@ -26,6 +26,9 @@ jobs:
       DEBUG: "true"
     steps:
     - uses: actions/checkout@v3
+    - name: Remove bundler version pin for head Ruby
+      if: matrix.ruby == 'head'
+      run: sed -i '/^BUNDLED WITH/{N;d}' Gemfile.lock
     - name: Set up Ruby ${{ matrix.ruby }}
     # To automatically get bug fixes and new Ruby versions for ruby/setup-ruby,
     # change this to (see https://github.com/ruby/setup-ruby#versioning):